The balance is part of the escapement, which is the organ responsible for both letting down the wound power of the mainspring, and regulating timekeeping. The "hourglass" sort of clip over the round jewel is a spring clip designed to allow some free play of the balance staff during vertical and horizontal movement of the pivot, and serves as shock protection. The thin coils represent the balance spring or "hairspring," the length of which will determine the frequency with which the balance wheel will oscillate. A small portion of the balance wheel is seen at the extreme lower left as an arc. The toothed wheel is part of the gear train.