▁Australian ▁armed ▁forces ▁is ▁such ▁a ▁device . ▁The ▁g rip ▁may ▁also ▁have ▁a ▁tact ical ▁light ▁and ▁the ▁control ▁switch es ▁m old ed ▁into ▁the ▁g rip ' s ▁assembly . ▁ ▁Other ▁designs ▁may ▁contain ▁storage ▁space ▁for ▁spare ▁parts , ▁spare ▁batter ies ▁for ▁opt ics , ▁weapon ▁lights , ▁or ▁small ▁first ▁aid ▁g ear . ▁Some ▁designs ▁may ▁have ▁a ▁bottom ▁that ▁threads ▁on ▁with ▁an ▁O - ring ▁to ▁make ▁this ▁storage ▁compart ment ▁wat ert ight . ▁ ▁St ub by ▁g rip ▁ ▁A ▁shorter ▁version ▁is ▁referred ▁to ▁as ▁a ▁" st ub by ▁g rip " ▁and ▁is ▁primarily ▁intended ▁to ▁keep ▁the ▁shoot er ' s ▁hand ▁from ▁moving ▁forward ▁of ▁the ▁m uzz le . ▁ ▁Ang led ▁forward ▁g rip ▁▁ ▁Ang led ▁forward ▁g ri ps ▁can ▁provide ▁similar ▁functionality ▁to ▁vertical ▁forward ▁g ri ps . ▁One ▁such ▁popular ▁product ▁is ▁the ▁Mag P ul ▁Dynam ics ▁AF G , ▁or ▁Ang led ▁Fore ▁G rip . ▁This ▁allows ▁the ▁operator ▁to ▁lay ▁the ▁pal m ▁of ▁their ▁hand ▁onto ▁the ▁g rip ▁while ▁pushing ▁the ▁thumb ▁down ▁on ▁the ▁top ▁of ▁the ▁gun . ▁ ▁Leg ality ▁on ▁p ist ols ▁in ▁the ▁U . S . ▁ ▁The ▁leg ality ▁of ▁vertical ▁for eg ri ps ▁on ▁p ist ols ▁in ▁the ▁United ▁States ▁is ▁unclear . ▁In ▁the ▁United ▁States , ▁fire ar ms ▁are ▁categor ized ▁by ▁the ▁National ▁Fire ar ms