The Fontainemelon 608-21 watch movement is a pocketwatch caliber available in options of 18.5 and 19''' with heights of 4.2, 5.0, and 5.9mm. It features a bimetallic screw balance and Breguet hairspring. The movement offers various bridge layouts and two base plates with different dial-feet positions. Additionally, there are slight variations in the setting-lever springs. The specific assignment of these differences to the FHF groups and calibers is partially known. The movement belongs to the FHF 1 to FHF 14 group, with individual designations starting from FHF 22. The Fontainemelon 608-21 movement offers functions such as stem wind and set, sub second display, and right setting. It was primarily used around the period of 1930.