FIELD OF THE INVENTION 
     Embodiments of the present invention relate to mechanical couplers that enable coupling and decoupling without the use of tools for releasably coupling an object to a support and rotationally positioning the object relative to the support, and in particular for coupling a recording device (e.g., digital video recorder, microphone, camera) to a clothing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       Embodiments of the present invention will be described with reference to the drawing, wherein like designations denote like elements, and: 
         FIG. 1  is a front view of a digital video recorder (“DVR”) coupled to a clothing (e.g., support) and positioned by the coupler according to various aspects of the present invention; 
         FIG. 2  is a side plan view of the DVR, coupler and support of  FIG. 1 ; 
         FIG. 3  is a exploded plan view that is to scale of the ring, cover, and base of the coupler of  FIG. 2 ; 
         FIG. 4  is a cross-sectional view of the DVR, coupler, and support of  FIG. 2  along a center vertical (e.g., top to bottom on page) axis; 
         FIG. 5  is a rear view that is to scale of the coupler of  FIG. 2  with the coupler in a locked position and the support removed for viewing; 
         FIG. 6  is a front view of the ring of the coupler; 
         FIG. 7  is a rear view of the base and the ring, absent the cover for clarity of presentation, with the coupler in the decoupled (e.g., inserted) position; 
         FIG. 8  is the rear view of the base and ring of  FIG. 7  with the coupler in an intermediate position; 
         FIG. 9  is the rear view of the base and ring of  FIG. 7  with the coupler in a locked position; 
         FIG. 10  is a side view of the base of the coupler; and 
         FIG. 11  is a diagram of forces required to rotate a base from a decoupled position, through an intermediate position, to a locked position. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The coupler of the present invention may be used to couple any suitable object to any suitable support. The coupler of the present invention may be used to position (e.g., orient) an object with respect to a support. In an implementation, the coupler of the present invention releasably couples a DVR to equipment (e.g., clothing, uniform, belt, glasses, hat, helmet, shirt, backpack, wristband, harness) used and/or worn by a person (e.g., witness, participant, user, investigator, police officer). In an implementation, coupler  200  of  FIGS. 1-10  includes base  210 , cover  220 , and ring  310 . 
     A base is the portion of the coupler that couples (e.g., attaches, connects) to the object. The cover is the portion of the coupler that couples to the support. The base releasably couples to the cover thereby releasably coupling the object to the support. A releasable coupler enables a user to remove the object from the support. 
     A base may be positioned (e.g., oriented) with respect to a cover so that an object may be positioned with respect to a support. 
     The base may be release from or coupled to the cover without the use of tools. So, an object may be coupled to a support manually by a person without the use of tools. Because the coupler is releasable, an object may be released (e.g., removed) from one support and coupled to another support that includes a cover for receiving the base coupled to the object. 
     A base may be coupled to an object so that it may not be easily removed from the object. A cover may be coupled to a support so that it may not be easily removed from the support. The base may be coupled to an object at an orientation and the cover coupled to a support at an orientation so that when the base is releasably coupled to the cover, the object is positioned (e.g., oriented) with respect to the support. The orientation of the object with respect to the support may facilitate the operation (e.g., use, function) of the object. 
     A base may move closer to (e.g., in, toward) and away from (out, outward) from a cover. Because the base couples to an object and a cover couples to a support, as the base moves toward and away from the cover, the object moves toward and away from the support. A base may move closer to and away from a cover along an axis. When the base moves toward the cover along the axis, a portion of the base may be inserted (e.g., enter) into a portion of the cover. A base may rotate (e.g., turn) with respect to a cover. Because the base couples to an object and a cover couples to a support, the base may rotate as a result of a user rotating the object with respect to the support. 
     As discussed herein, movement of the base with respect to the cover discloses movement of the object with respect to the support because the base couples to the object and the cover couples to the support. Any discussion of movement of the base also describes movement of the object and vice versa. Any discussion of the cover relates to the support because the cover couples to the support. In an implementation where the base couples to a DVR and the cover couples to the clothing of a user, the user does not directly contact the base to move and/or rotate the base. The user manually positions the object so that the base is positioned with respect to the cover and with respect to the clothing. The user manually rotates the object so that the base rotates with respect to the cover and with respect to the clothing. 
     While the portion of the base is inserted into the cover, the base may rotate with respect to the cover. Rotating the base after inserting portion of the base into the cover causes a portion of the cover to interfere with (e.g., obstruct, stop) movement of the base away from the cover along the axis thereby coupling the base to the cover. The base remains coupled to the cover as long as the cover interferes with movement of the base away from the cover or vice versa. 
     A ring positioned in the cover may retain (e.g., hold, interfere with) a base that is inserted into a cover at a particular rotated position (e.g., orientation). While a ring holds a base that is inserted into a cover at a rotated position, the base cannot be separated from (e.g., move away) the cover, thereby coupling the base to the cover and in turn the object to the support. A ring may hold a base at one or more rotated positions (e.g., orientations). A ring may hold a base, and therefore an object, at a position that provides an environment for proper operation of the object. 
     A base may couple to an object using any conventional technique for coupling. In an implementation, base  210  includes bores  350  for coupling to an object by screw and/or bolt. A cover may couple to a support using any conventional technique for coupling. In an implementation, cover includes bores  332  for coupling to a support by screw and/or bolt. In another implementation, the cover is sewn to the support. In another implementation, the cover is coupled to a structure that is coupled to the support. In an implementation, the cover is coupled to a piece of material (e.g., plastic, cloth) that in turn is sewn to the clothing of a user. In another implementation, the cover is coupled to magnetic material that magnetically couples to the support. 
     In an implementation, the coupler of the present invention releasably couples a DVR to equipment worn by a person. The coupler retains the DVR coupled to the equipment, permits the DVR to be manually removed from or coupled to the equipment, and positions the DVR to record information that occurs in the vicinity of the person. In  FIG. 1 , DVR  120  (e.g., object) couples to uniform  130  (e.g., support) worn by officer  110  so that DVR  120  may record the events that occur in the vicinity of officer  110  thereby performing the function of a body-worn recording system. As shown in  FIGS. 1-2 and 4 , coupler  200  couples DVR  120  to uniform  130 . 
     Base  210  that couples to the object includes post  340  having axis  360 , surface  380 , plate  392 , and bores  350 . Cover  220  that couples to a support includes surface  336 , opening  330  in surface  336 , surface  338 , bores  332 , recess  334 , and axis  362 . Ring  310  includes arm  312 , arm  314 , arm  316 , arm  318 , stop  372 , stop  374 , opening  320 , and axis  364 . End portion  610  of arm  312  includes ramp  612  and face  314 . End portion  620  of arm  314  includes ramp  622  and face  624 . End portion  630  of arm  316  includes ramp  632  and face  634 . End portion  640  of arm  318  includes ramp  642  and face  644 . Because end portions  610 - 640  increase in width from ramp  612 - 642  to the end of each end portion, end portions  610 - 640  may be described as bulbous. 
     Base  210  performs the functions of a base discussed above. Cover  220  performs the functions of a cover discussed above. Ring  220  performs the functions of a ring discussed above. 
     Post  340  of base  210  couples to and projects away from plate  392 . As discussed above, bores  350  may be used to couple base to an object (e.g., DVR). While base  210  is coupled to an object, surface  380  faces way from the object. Post  340  includes protrusion  342 , protrusion  344 , protrusion  346 , and protrusion  348 . Protrusions  342 - 348  project away from (e.g., out of) post  340 . Protrusions  342 - 348 , as discussed below, interfere with portions of cover  220  to couple base  210  to cover  220 . 
     Protrusions  342 - 348  extend a distance away from center portion  382  of post  340 . Protrusions  342  and  344  extend farther away from center portion  382  than protrusions  346  and  348 . The length of the projection of protrusions  342 - 348  from post  340  may be measured with respect to axis  360 . Protrusions  342  and  344  extend a distance  1030  from axis  360 . Protrusions  346  and  348  extend a distance  1040  from axis  360 . Underside (e.g., undersurface)  1010  of protrusions  342 - 348  is positioned a distance  1020  away from surface  380  so that slot  410  is formed between undersurface  1010  and surface  380 . As discussed below, a portion of cover  220  enters (e.g., engages, interlocks) slots  410  so that underside  1010  contacts surface  336  to couple base  210  to cover  220 . 
     Base  210  may be formed of any material or combination of materials that have suitable properties to perform the functions of a base. Such materials may include metals, plastics, composite materials, or any combination thereof. In one implementation, base  210  is formed of aluminum. In another implementation, base  210  is formed of a durable plastic. Preferably, the material that forms base  210  has sufficient strength so that when base  210  is rotated out of the decoupled position toward the intermediate position, the strength of protrusions  342 - 348  is sufficient to not break or deform, under normal use, so that base  210  separates from cover  220  and ring  310 . 
     In an implementation in which base  210  is formed of aluminum, thickness  1022  of base  210  from surface  1024  opposite  380  to upper surface  384  is about 5 millimeters (mm). Thickness  1026  of plate  392  of base  210  is about 1.4 mm. The distance between underside  1010  of protrusions  342 - 348  and surface  380  is about 1 mm. Length  390  of each side of plate  392  is about 42 mm a side. 
     Arms  312 - 318  of ring  310  are formed of a resilient material so that when an arm is pushed (e.g., forced, moved) outwardly (e.g., away from the center, away from the central axis, away from axis  364 ), the arm will return to its original position when the force is removed. Further, when arms  312 - 318  are forced outwardly, the resilient nature of the material used to form arms  312 - 318  means that  312 - 318  will apply a force against the object that pushes the arm outwardly. 
     Recess (e.g., cavity, depression)  334  of cover  220  is of a shape to accept ring  310  so that ring  310  may be positioned in recess  334 . The shape of recess  334  and the corresponding shape of ring  310  include surfaces that interfere with (e.g., block, collide with, hinder) each other (e.g., edges of surface  334 , edges of ring  310 ) so that when a rotational force is applied to ring  310 , ring  310  will not turn (e.g., rotate) in recess  334 . 
     The depth (e.g., height) of recess  334  is sufficient so that when ring  310  is positioned in recess  334  that upper surface  376  of ring  310  is flush with or below surface  338  of cover  220 . When cover  220  is coupled to a support, recess  334  with ring  310  positioned in recess  334  are oriented toward the support and surface  338  comes into contact with the surface of the support. If upper surface  376  of ring  310  is flush with surface  338 , the support will not interfere (e.g., block, collide with, hinder) with movement of arms  312 - 318 . If the height of post  340  is less than the depth of recess  334 , the support will not interfere with the rotation of post  340  when it is inserted into cover  220 . 
     Openings  320  and  330  are of a shape and size so that post  340  with protrusions  342 - 348  may pass through openings  320  and  330  when base  210  is positioned in a position for insertion into opening  330  of cover  220 . The position of base  210  with respect to cover  220  and ring  310  when oriented so that post  340  may be inserted into openings  320  and  330  is referred to herein as the decoupled (e.g., insertion) position. In the insertion position, axis  360  of base  210  is aligned with axis  362  of cover  220  and axis  364  of ring  310 . Ring  310  is positioned in recess  334 . Base  210  is rotated until protrusions  342 - 348  align with the sides of opening  330  and opening  320 . Base  210  is then moved toward cover  220  so that post  340  passes into opening  330  and opening  320 . Base  210  may be moved toward cover  220  until it stops when surface  380  touches cover  220 . The position of post  340  relative to opening  320  while in the decoupled position is show in  FIG. 7 . 
     As discussed above, when base  210  is in the decoupled position and is move as close is it can to cover  220 , upper surface  384  of post  340  does not extend above (e.g., beyond, past) surface  338  of cover  220 . In  FIG. 3 , post  340  is not in the decoupled position because protrusions  342 - 348  are rotated about 90 degrees with respect to cover  220  so that protrusions  342 - 348  cannot fit through opening  330  or opening  320 . When ring  310  is positioned in recess  334 , opening  320  aligns with opening  330  so that protrusions  342 - 348  may pass into openings  330  and  320  when base  210  is oriented in the decoupled position. 
     When base  210  is in the decoupled position and inserted into openings  320  and  330 , cover  220  (e.g., edges around opening  330 ) are not positioned in slots  410  between underside  1010  and surface  380 . However, when base  210  is rotated, in this implementation counterclockwise from the perspective of  FIGS. 5 and 7-9 , the edges of cover  220  around opening  330  enter slot  410  between protrusions  342 - 348  and surface  380 . Once cover  220  is positioned in slots  410 , base  210  cannot be pulled away from cover  220  because underside  1010  of protrusions  342 - 348  interferes with (e.g., block, collide with, hinder, contacts) surface  336  so base  210  cannot be extracted (e.g., decoupled, pulled away) from cover  220 . 
     In  FIG. 4 , base  210  is inserted through openings  320  and  330  and rotated out of the decoupled position. Portions of cover  220  are positioned in slots  410  formed between underside  1010  of protrusions  342 - 348  and surface  380 . In  FIG. 5 , base  210  is show in the locked position, which is discussed below. Because base  210  is not in the decoupled positioned, cover  220  is positioned in slots  410 . In  FIG. 5 , protrusions  342 - 348  are shown positioned over surface  336  of cover  220 . Base  210  cannot be pulled out of opening  330  because protrusions  342 - 348  contact surface  336  and interfere with the removal of base  210 . 
     Rotating base  210  back to the decoupled position moves protrusions  342 - 348  so that cover  220  exits slots  410 . Once cover  220  exits slots  410 , base  210  is in the decoupled position and base  210  may be extracted from holes  320  and  330  by moving base  210  along axis  360 / 362 / 364 , (axis are aligned in decoupled position) away from cover  220 . 
     As discussed briefly above, ring  310  retains base  210  in one or more rotated positions. In an implementation, ring  310  and in particular arms  312 - 318  and stops  372 - 374 , operate to hold base  210  in two positions referred to herein as an intermediate position and a locked position. 
       FIG. 7-9  omit cover  220  to clarify the cooperation of ring  310  with post  340  to hold base  210  at various orientations. While base  210  is positioned in the decoupled position, as shown in  FIG. 7 , arms  312 - 318  do not apply a force on post  340 . As discussed above, while base  210  is in the decoupled position, base  210  may be separated from cover  220  and ring  310  because no portion of ring  310  or cover  220  interfere with the movement of base  210  away from cover  220  and/or ring  310 . 
     Graft  1100  of  FIG. 11  represents the relative force to rotate base  210  from the decoupled position to the locked position. The decoupled position is represented by orientation  710 . 
     From the decoupled position, base  210  may be rotated, counterclockwise from the perspective of  FIGS. 5 and 7-9 . The orientation of the protrusions  342 - 348  with respect to ring  310  in the decoupled position is identified as orientation  710 . Rotating base  210  angular distance  820  from orientation  720  to orientation  810  moves base  210  from the decoupled position to the intermediate position. Further rotating base  210  angular distance  920  from orientation  810  to orientation  910  moves base  210  from the intermediate position to the locked position. Under proper operating conditions, base  210  does not rotate further counterclockwise past the locked position. 
     Base  210  may be rotated, clockwise from the perspective of  FIGS. 5 and 7-9 , from the locked position to the intermediate position. Base  210  may be further rotated from the intermediate position to the decoupled position. 
     Although the above description uses the terms counterclockwise and clockwise with respect to coupling and decoupling respectively, any direction of rotation may be used for coupling and the opposite direction for decoupling so that coupling is not limited to counterclockwise rotation and decoupling is not limited to clockwise rotation. 
     As base  210  rotates with respect to ring  310  and cover  220 , arms  312 - 318  cooperate with (e.g., interact with, operate on, interfere with) protrusions  342 - 348 . As base  210  rotates from the decoupled position at orientation  710  toward intermediate position at orientation  810 , protrusions  342  and  344  push against ramps  612  and  632  respectively. Ramps  612 ,  622 ,  632 , and  642  are positioned at an angled, as opposed to orthogonal, to with respect to faces  614 ,  624 ,  634 , and  644  respectively so that protrusions  342  and  344  may apply less on arms  312 - 318  to cause arms  312 - 318  to deflect (e.g., bend, flex) away from the center of ring  310  which corresponds to axis  360 / 364 . 
     As base  210  rotates from orientation  710  to orientation  810 , protrusions  342  and  344  push against ramps  612  and  632  respectively and cause arms  312  and  316  to move outward away from axis  360 / 364 . As base  210  continues to rotate counterclockwise, protrusion  342  and  344  move past ramps  612  and  632  respectively, and along face  614  and face  634  until protrusion  342  and  344  contact end portion  620  and end portion  640  respectively. The force required to rotate base  210  so that protrusions  342  and  344  pass ramps  612  and  632  respectively, shown as amount (e.g., level, magnitude) of force  1116  in  FIG. 11 , is greater than the amount of force  1114  required to rotate (e.g., move) protrusions  342  and  344  along faces  614  and  634 . The force required to rotate protrusions  342  and  344  past ramps  626  and  646  of end portions  620  and  640  respectively, amount of force  1118 , is greater than the force, amount of force  1114 , required to rotate protrusions  342  and  344  along faces  614  and  634  and greater than the force, amount of force  1116 , required to rotate protrusions  342  and  344  along ramps  612  and  632 , so when protrusions  342  and  344  contact end portions  620  and  640  respectively, the user turning base  210 , or the object coupled to base  210 , feels a definite stop (e.g., bump, pause) in the movement of base  210 , or object coupled to base  210 , upon reaching orientation  810 . 
     While base  210  is positioned at orientation  810  in the intermediate position, protrusions  342  and  344  push against end portions  610  and  630  so that arms  312  and  316  remain positioned away (e.g., distal, deflected) from axis  360 / 364 . Because arms  312  and  316  are formed of a resilient material, arms  312  and  316  apply a force on protrusions  342  and  344  respectively. The force applied by arms  312  and  316  on protrusions  342  and  344  operate to retain base  210  in the intermediate position. The interference of end portions  620  and  640  with protrusions  342  and  344  act to limit further counterclockwise rotation of base  210  without a further increase in the amount of force that operates on base  210  to cause it to rotate. 
     Ramps  626  and  646  of end portions  620  and  640  that are proximate to protrusions  342  and  344  while in the intermediate position are angled, as opposed to orthogonal, to faces  624  and  644  respectively to decrease the amount of force required to rotate base  210  over ramps  626  and  646  past the ends of arms  314  and  318 . However, the angle of ramps  626  and  646  with respect to faces  614  and  634  respectively is greater than the angle of ramps  612  and  632  with respect to faces  614  and  634  respectively, so the amount of force, amount of force  1118 , required to rotate protrusions  342  and  344  past ramps  626  and  646  is greater than the amount of force, amount of force  1116 , required to rotate protrusions  342  and  344  past ramps  612  and  632 . 
     Base  210  remains in the intermediate position as long as a force applied to base  210  in the clockwise direction is less than the force applied by arms  312  and  316  on protrusions  342  and  344  respectively and the force applied to base  210  in the counterclockwise direction is less than the force, amount of force  1118 , required to move protrusions  342  and  344  past ramps  626  and  646  of end portions  620  and  640 . 
     When a user applies the force, amount of force  1118 , required to move protrusions  342  and  344  along ramps  626  and  646  past the ends of end portions  620  and  640 , base  210  begins to rotate from orientation  810  toward orientation  910 . Protrusions  342  and  344  push arms  314  and  318  outward away from axis  360 / 364  as protrusions  432  and  344  move along ramps  626  and  646  respectively. As protrusions  342  and  344  move down ramps  616  and  636  and past end portions  610  and  630 , arms  312  and  316  move toward axis  360 / 364  until they return to their original positions. Further, as protrusions  342  and  344  move past arms  312  and  316 , the force applied by arms  312  and  316  on protrusions  342  and  344  decreases. 
     Protrusions  342  and  344  push arms  314  and  318  outward as protrusions  342  and  344  move along ramps  626  and  646  until protrusions  342  and  344  reach faces  624  and  644 . As base  210  continues to rotate, protrusions  342  and  344  move along face  624  and  644  respectively. The force, amount of force  1114 , required to move protrusions  342  and  344  along face  624  and  644  respectively, is less than amount of force  1118  and amount of force  1116 . While arms  314  and  318  are pushed outward by protrusions  342  and  344 , arms  314  and  318  apply a force on protrusions  342  and  344 . Base  210  continues to rotate counterclockwise until protrusions  342  and  344  reach ramps  622  and  642  respectively. As protrusions  342  and  344  reach ramps  622  and  642  respectively, the force required to rotate base  210  in a counterclockwise direction down ramps  622  and  642  decreases because of the orientation of ramps  622  and  642  with respect to faces  624  and  644  and because the force applied by arms  314  and  318  on protrusions  342  and  344  helps to move protrusions  342  and  344  down ramps  622  and  642 . The force, amount of force  1112 , required to move protrusions along ramps  622  and  642  is less than amount of force  1114 ,  1116 , and  1118 . 
     After protrusions  342  and  344  have cleared (e.g., moved past) ramps  622  and  642 , protrusions  342  and  344  contact stops  372  and  374  respectively and base  210  is positioned at orientation  910 . While at orientation  910 , base  210  is in the locked position. 
     Amount of force  1118  required to rotate base  210  so that protrusions  342  and  344  move counterclockwise along ramps  626  and  646  past the ends of end portions  620  and  640  respectively is greater than the force, amount of force  1114 , required to rotate protrusions  342  and  344  along faces  624  and  644  respectively. Amount of force  1112  required to rotate base  210  so that protrusions  342  and  344  pass along ramps  622  and  642  respectively is less than the force, amount of force  1114 , required to move protrusions  342  and  344  along faces  624  and  644  respectively. When protrusions  342  and  344  contact stops  372  and  374  respectively base  210  stops rotating and base  210  is at orientation  910 . 
     Stops  372  and  374  do not include angled surfaces. Stops  372  and  374  contact a portion of protrusions  342  and  344  respectively that is closer to axis  360 / 364 , as opposed to a portion closer to an end portion of protrusions  342  and  344 , to increase the force required to move protrusions  342  and  344  past stops  372  and  374 . Under proper operation, base  210  does not rotate counterclockwise past orientation  910 . Rotating base  210  counterclockwise past orientation  910  would require breaking off stops  372  and  374 . Amount of force  1120  required to rotate base  210  past stops  372  and  374  represents a force that is significantly greater than amount of force  1112 ,  1114 ,  1116 , and  1118 . 
     While base  210  is positioned at orientation  910  in the locked position, stops  372  and  374  stop (e.g., limit, impair, halt) further counterclockwise rotation while at the same time end portions  620  and  640  resist clockwise rotation. While base  210  is in the locked position, arms  314  and  316  may apply some pressure on protrusions  342  and  344  and end portions  620  and  640  may apply some pressure on protrusions  346  and  348  respectively to resist clockwise movement of base  210  out of orientation  910 . 
     The forces show in  FIG. 11  are relative to each other and are not absolute representations of force. The levels of force in  FIG. 11  are not to scale and show only a relative increase or decrease of the amount of force. The positive or negative slope in the line of graph  1100  has no meaning. The change in force to rotate base  210  may occur with little change in the orientation of base  210  or base  210  may rotate slightly as the level of force increases or decreases between the levels of force (e.g.,  1112 ,  1114 ,  1116 ,  1118 ) shown in  FIG. 11 . 
     At orientation  1130 , protrusions  342  and  344  start to move along ramps  612  and  632  respectively. At orientation  1132 , protrusions  342  and  344  start to move off of ramps  612  and  632  and along faces  614  and  624  respectively. At orientation  810 , base  210  is in the intermediate position. At orientation  1140 , protrusions  342  and  344  start to move along ramps  626  and  646 . The force required to for protrusions  342  and  344  to move down ramps  616  and  636  is not shown because movement down ramps  616  and  636  occurs after movement of protrusions  342  and  344  up ramps  626  and  646 . At orientation  1142 , protrusions  342  and  344  start to move off of ramps  626  and  646  respectively and along faces  624  and  644  respectively. At orientation  1144 , protrusions  342  and  344  start to move down ramps  622  and  642 . 
     Many factors affect the force required to rotate base  210  from one orientation to another orientation. Factors include the resilient force applied by each arm  312 - 318  on protrusions  342 - 348 , the orientation (e.g., angles) between surfaces on ring  310 , the shape of protrusions  342 - 348 , in particular the shape of protrusions  342  and  344 , and a coefficient of friction between protrusions  342 - 348  and the surfaces of ring  310 . 
     Protrusions  342  and  344  are diametrically (e.g., oppositely, 180 degree difference, mirrored) positioned with respect to each other across axis  360 . Protrusions  346  and  348  are also diametrically positioned with respect to each other across axis  360 . When protrusions  342  or  346  are positioned so that arms  312  or  314  applies a force to protrusion  342  or  346 , an opposite, and preferably equal, force is apply by arms  316  and  318  to protrusion  344  and protrusion  348 . Arms  312 - 318  are positioned symmetrically (e.g., mirrored) in ring  310 . Arms  312  and  316  are positioned opposite each other across axis  364 . Arms  314  and  318  are positioned opposite each other across axis  364 . Because protrusions  342  and  344  are positioned opposite each other across axis  360 , when arm  312  applies a force to protrusion  342 , protrusions  344  is positioned so that arm  316  applies an opposing force (e.g., force in opposite direction to arm  312 ) to protrusion  344  at the same time. When arm  314  applies a force to protrusion  342 , protrusion  344  is positioned so that arm  318  applies an opposing force to protrusions  344  at the same time. When arm  314  applies a force to protrusion  346 , protrusion  348  is positioned so that arm  318  applies an opposing force to protrusion  348 . Opposing arms interact with and operate on opposing protrusions at the same time. 
     The simultaneous opposing (e.g., symmetrical) forces that are applied to protrusions  342 - 348 , as discussed above, result from symmetry of arms  312 - 318  in ring  310 . The symmetrical application of force by arms  312 - 318  on protrusions  342 - 348  improves retention of base  210  at any particular rotated orientation. The symmetry of arms  312 - 318  and protrusions  342 - 348  causes arm pair  312 / 316  and arm pair  314 / 318  to operate against protrusions  342 / 344  and  346 / 348  to apply opposing forces to post  340  to retain base  210  at rotated positions. 
     Because arms  312  and  316  cooperate with each other and arms  314  and  318  cooperate with each other to respectively apply force on post  340 , arm pair  312 / 316  may operate distinctly from air pair  214 / 318 . For example, the resilient material that forms arm pair  312 / 316  may be different from the resilient material that forms arm pair  314 / 318  so that arms of a pair apply the same amount of force on post  340  while arm pairs apply a different amount of force on post  340 . For example, arm pair  314 / 318  may be formed of a more resilient (e.g., stiffer, springier) material than used to form arm pair  312 / 316  so that rotating base  210  from decoupled position  710  to intermediate position  810  takes less force than rotating base  210  from intermediate position  810  to locked position  910 . The same may be done in reverse so that arm pair  314 / 318  is formed of a more resilient material than arm pair  312 / 316  so that more force is required to rotate base  210  from decoupled position  710  to intermediate position  810  than from intermediate position  810  to locked position  910 . 
     Preferably, each arm of arm pair  312 / 316  and arm pair  314 / 318  have the same resilient characteristics so that the force applied by the arms of an arm pair on post  340  is about equal in the amount of force and opposing in direction. 
     The orientations where base  210  is retained (e.g.,  810 ,  910 ) may be at any position along an arc. The angular distances between orientations where base  210  is retained may be equal or different. An angular distance from one orientation to another orientation may be the same or different. For example, angular distance  820  and  920  may be the same or different. Angular distance  820  may be greater than angular distance  920  or vice versa. 
     To decoupled base  210  from cover  220 , base  210  is rotated from the locked position at orientation  910 , to the intermediate position at orientation  810 , and from the intermediate position to the decoupled position at orientation  710 . 
     From the stopped position, rotating base  210  clockwise, with respect to  FIGS. 7-9 , forces protrusions  342  and  344  against ramps  622  and  642  respectively. As protrusions  342  and  344  travel along ramps  622  and  642 , protrusions push arms  314  and  318  outward away from  360 / 364 . As arms  314  and  318  are pushed outwardly, arms  314  and  318  apply a force on protrusions  342  and  344  respectively. As base  210  continues to rotate clockwise, protrusions  342  and  344  move across faces  624  and  644  until a portion of (e.g., edge) of protrusions  342  and  344  contact the ends of end portions  610  and  630  of arms  312  and  316 . Contact with end portions  610  and  630  creates an greater resistance to rotation in the clockwise direction that requires additional force to overcome to continue clockwise rotation. 
     This position, when protrusions  342  and  344  contact the ends of end portions  610  and  630  of arms  312  and  316 , may be referred to as the intermediate return position. The intermediate return position is not the same as the intermediate position. The orientation of the intermediate return position lies between orientation  810  and  910 . 
     While base  210  is positioned in the intermediate return position, protrusions  342  and  344  push arms  314  and  318  respectively outward. Because arms  314  and  318  are arm formed of a resilient (e.g., springy, elastic) material, while arms  314  and  318  are pushed outward, they exert a force on protrusions  342  and  344  that acts to maintain base  210  in the intermediate return position. 
     From the intermediate return position, applying additional force pushes protrusions  342  and  344  with greater force against end portions  610  and  630 . End portions  610  and  630  may include an angle so that the end of end portions  610  and  630  are not orthogonal to face  614  and  634  respectively. As protrusions  342  and  344  push on (e.g., cooperate with, interact with, operate on) end portions  610  and  630 , arms  312  and  316  begin to move outwardly away from axis  360 / 364 . As protrusions  342  and  344  move along face  614  and  634 , protrusions  342  and  344  move past arms  314  and  318  so that arms  314  and  318  move inwardly toward axis  360 / 364 . When protrusions  342  and  344  clear end portions  620  and  640  of arms  314  and  318 , arms  314  and  318  move back to their original position. 
     As base  210  continues to rotate clockwise, protrusions  342  and  344  move across faces  614  and  634  respectively, and across ramps  612  and  632  until protrusions  346  and  348  contact stops  374  and  372  respectively. Clockwise rotation stops when protrusions  346  and  348  contact stops  374  and  372  and base  210  is in the decoupled position at orientation  710 . 
     From the stopped position, the force required to move protrusions  342  and  344  clockwise along ramps  622  and  642  respectively is greater than the force required to move protrusions  342  and  344  clockwise along faces  624  and  644 . Once protrusions  342  and  344  have contacted the end of end portions  610  and  630 , the force to continue clockwise rotation in greater than the force required to move protrusions  342  and  344  along faces  624  and  644 . The force required to move protrusions  342  and  344  along faces  614  and  634  respectively is less than the force required to move protrusions  342  and  344  past the end of end portions  610  and  630 . The force required to move protrusions  342  and  344  along ramps  612  and  632  is less than the force required to move protrusions  342  and  344  along faces  624  and  644 . 
     Once protrusions  346  and  348  contact stops  374  and  372  respectively, the force required for continued clockwise movement is very high. In normal operation, base  210  cannot rotate in a clockwise direction past orientation  710 . The force required to move past stops  372  and  374  would break stops  372  and  374 . 
     Once base  210  is back in the decoupled position at orientation  710 , base  210  may be separated from cover  220  and ring  310 . 
     As discussed above, while base  210  is coupled to cover  220 , upper surface  384  of base  210  does not extend above (e.g., beyond) surface  338  of cover  220  or surface  376  of ring  310 . So, the entire thickness (e.g., width) of coupler  200  may be the same or slightly more than the width of base  210 . For example, in an implementation, base  210  has thickness  1022 . If upper surface  384  does not extend past surface  388  or surface  376 , coupler  200  may have a thickness that is about the same as thickness  1022 . If upper surface  384  does not quite reach the same level as surface  338  (e.g., it is below), then the thickness of coupler  200  may be more than thickness  1022  by the amount of difference between upper surface  384  and surface  338 . 
     In light of the construction and thickness  1022  of base  210 , coupler  200  may be relatively thin (e.g., low profile) when compared to the objects to which base  210  may be attached. For example, for DVR that has a thickness of 0.8 inches (i.e., 20.32 mm), connector  200  with a thickness of only 5 mm is only one quarter of the thickness of the DVR. 
     In an implementation, coupler  200  may couple a DVR to a person. A DVR coupled to a person may be used to record an event (e.g., occurrence, incident). In accordance with the above discussion, base  210  couples to DVR  120 , cover  220  couples to the uniform  130  of the officer  110 . Ring  310  is positioned in recess  334 . 
     Officer  110  couples DVR  120  to uniform  130  by rotating camera so that base  210  is oriented at orientation  710 . While DVR  120  is rotated so that base  210  is oriented at orientation  710 , the lens of DVR is not oriented upright, so any video taken by DVR  120  while base  120  is in position  720  would be rotated about 90 degrees to the right so that the heads of people standing upright would be oriented to the right side of the picture. 
     While DVR  120  is rotated so that base  210  is at orientation  710 , officer  110  aligns axis  360  of base  210  with axis  362  of cover  220  and  364  of ring  310  and inserts post  340  into opening  330  and aligned opening  320  until surface  380  touches cover  220 . Base  210  is now in the decoupled position. 
     Officer  110  rotates DVR  120  counterclockwise, from the perspective of officer  110 , until officer feels increased resistance and possibly hears an audible clicking sound of protrusions  342  and  344  hitting the end of end portions  620  and  640 . At this orientation, base  210  is in the intermediate position. Even though the force applied by arms  312  and  316  on protrusions  342  and  344  may hold base  210  and therefore DVR  120  in the intermediate position, DVR  120  is still oriented at an angle with respect to the officer so the video recorded by DVR  120  in the intermediate position would not show upright objects as being upright. 
     Officer  110  applies more force to rotate DVR  120  further counterclockwise past the intermediate position until officer  110  feels increase resistance and possible an audible click as protrusions  342  and  344  hit against stops  372  and  374  respectively. At this orientation, base  210  is in the locked position and oriented at orientation  910 . In the locked position, DVR  120  is properly oriented for recording video at an angle where the objects in the recorded video will be oriented at the same orientation as viewed by officer  110 . For example, the head of people who are standing or are upright will be oriented toward the top of the recorded video. 
     To accomplish positioning DVR  120  at an orientation for proper operation while base  210  is in the locked position, DVR  120  must be oriented with respect to base  210 , base  210  must be oriented with respect to cover  220  and cover  220  must be oriented with respect to uniform  130  so that rotating base  210  to the lock position results in positioning DVR  120  at the desired orientation for proper operation. 
     DVR  120  may be decoupled from uniform  130  by rotating DVR  120  clockwise from the perspective of officer  120  until base  210  is in the decoupled position then officer  120  may pull base  210  away from cover  220  to accomplish decoupling and complete separation of base  210  from cover  220  and ring  210  thereby decoupling DVR  120  from the uniform of officer  110 . 
     In an implementation, the strength of coupling between base  210  and cover  220  (e.g., coupling of base  210  to cover  220 ) may be increase by using a magnetic force to attract base  210  to cover  220  and vice versa. A magnetic attraction between base  210  and cover  220  may be used in addition to the force applied by ring  310  to retain base  210  at an orientation. Ring  210  may be formed of a non-magnetic material so that a magnetic force do not interfere with the operation of ring  310  to hold base  210  at an orientation as discussed above. A magnetic attraction between base  210  and cover  220  may be used to couple base  210  to cover  220  in addition to the interference between cover  220  and surface  1010  while portions of cover  220  are positioned in slot  410 . 
     Base  210  may be formed of a material or include material that provides a magnetic force and cover  220  may be formed, in whole or part, of a material that is attracted by the magnetic force provided by base  210  or visa versa. The magnetic force cannot be so strong that once base  210  and cover  220  contact each other that base  210  cannot be rotated, due to the magnitude of the magnetic force, to position the object coupled to base  210 . The magnetic force cannot be so strong that is it extremely difficult to separate base  210  from cover  220  while base  210  is in the decoupled position. 
     The magnetic coupling is not likely to be used alone (e.g., user forgets to rotate base  210 ) to couple base  210  to cover  220  because rotation of the object coupled to base  210  orients the object, in this case a DVR, for proper operation such as capturing video at the proper orientation as discussed above. 
     In an implementation, all or part of plate  392  is formed of a magnetic material (e.g., permanent magnet) while all or part of cover  220  is formed of a material (e.g., ferromagnetic) that is attracted to a magnetic field. In another implementation, all or part of cover  220  is formed of a magnetic material while all or part of plate  392  is formed of a ferromagnetic material. 
     The foregoing description discusses preferred embodiments of the present invention, which may be changed or modified without departing from the scope of the present invention as defined in the claims. Examples listed in parentheses may be used in the alternative or in any practical combination. As used in the specification and claims, the words ‘comprising’, ‘including’, and ‘having’ introduce an open ended statement of component structures and/or functions. In the specification and claims, the words ‘a’ and ‘an’ are used as indefinite articles meaning ‘one or more’. When a descriptive phrase includes a series of nouns and/or adjectives, each successive word is intended to modify the entire combination of words preceding it. For example, a black dog house is intended to mean a house for a black dog. While for the sake of clarity of description, several specific embodiments of the invention have been described, the scope of the invention is intended to be measured by the claims as set forth below. In the claims, the term “provided” is used to definitively identify an object that not a claimed element of the invention but an object that performs the function of a workpiece that cooperates with the claimed invention. For example, in the claim “an apparatus for aiming a provided barrel, the apparatus comprising: a housing, the barrel positioned in the housing”, the barrel is not a claimed element of the apparatus, but an object that cooperates with the “housing” of the “apparatus” by being positioned in the “housing”.
A coupler for removable coupling an object to a support. The coupler includes a cover, a ring, and a base. The cover couples to the support. The ring includes a first arm, a second arm, a third arm, a fourth arm, a first stop, and a second stop. Each arm of the ring is formed of a resilient material. The ring is positioned in a cavity of the cover. The base couples to the accessory. The base cooperates with the cover and the ring to couple to the cover and to rotate from a decoupled position to an intermediate position and further to a clocked position.