, ▁st ip ulating ▁the ▁performance ▁of ▁the ▁movement . ▁ ▁Of ▁the ▁millions ▁of ▁watch es ▁produced ▁in ▁Switzerland ▁each ▁year ▁by ▁all ▁manufact ur ers ▁in ▁the ▁mid - 1 9 6 0 s , ▁approximately ▁ 2 5 0 , 0 0 0 ▁would ▁receive ▁official ▁chron ometer ▁status ▁( similar ▁to ▁what ▁would ▁be ▁C OS C ▁standards ▁today ), ▁and ▁only ▁a ▁few ▁hundred ▁of ▁the ▁very ▁best ▁from ▁the ▁total ▁production ▁would ▁be ▁sent ▁to ▁an ▁observ atory ▁for ▁chron ometer ▁accuracy ▁compet itions . ▁Watch ▁movements ▁that ▁could ▁comp ete ▁for ▁accuracy ▁cert ification ▁at ▁the ▁observ atory ▁had ▁typically ▁been ▁specifically ▁built ▁for ▁that ▁purpose ▁alone , ▁they ▁were ▁slow ▁beat ▁movements , ▁oscill ating ▁at ▁from ▁ 1 8 , 0 0 0 ▁to ▁ 2 1 , 6 0 0   b ph , ▁typically ▁with ▁o vers ized ▁balance ▁whe els , ▁twe aked ▁and ▁prepared ▁by ▁the ▁best ▁watch m akers ▁often ▁for ▁many ▁years ▁to ▁render ▁ult imate ▁accuracy ▁before ▁they ▁were ▁submitted ▁to ▁the ▁observ atory . ▁Typ ical ▁examples ▁of ▁these ▁special ized ▁competition ▁movements ▁were ▁the ▁P ese ux ▁cal ▁ 2 6 0 , ▁the ▁Z en ith ▁cal ▁ 1 3 5 ▁and ▁the ▁Long ines ▁cal ▁ 3 6 0 . ▁Because ▁of ▁the ▁development ▁time ▁to ▁create ▁and ▁twe ak ▁such ▁movements , ▁watch ▁manufact ur ers ▁t ended ▁to ▁enter ▁very ▁few ▁movements ▁at ▁observ atory ▁compet itions . ▁ ▁Because ▁only