Index Regulator

Used to regulate the watch movement an index regulator is a metal component typically made from steel and made of two curb pins between which the circular balance-spring is held in place. The length of the balance spring is altered when the index regulator is used and can be used to regulate the movement in either direction determined by whether the watch is running fast or slow. Measurements marked on the balance cock are used as a guide to distinguish the estimated amount of adjustment required.

Many different types of index regulator systems exist although some manufacturers omit them and they adjust this when the watch is initially being made.