The Favre Leuba FRERES 18 watch movement is an open face calibre pocketwatch movement that offers options such as a bimetallic screw balance and a Breguet hairspring. It is available in several sizes, including 18.5 and 19''', with heights ranging from 4.2 to 5.9mm. The movement features various bridge layouts, two base plates with differing dial-feet positions, and two slightly differing setting-lever springs. While the specific assignment of these differences to the FHF movement groups and calibres is partially known, comparing the related calibres provides some understanding. The Favre Leuba FRERES 18 movement belongs to the FHF 1 to FHF 16 movement groups, with individual designations starting with FHF 22. It offers functions such as stem winding and setting, as well as a sub-second display. This movement was commonly used around the period of 1940.