The Certina 12-11 watch movement is an open face calibre which offers various options such as a bimetallic screw balance and a Breguet hairspring. These pocketwatch calibres are available in sizes 18.5 and 19''', with heights ranging from 4.2mm to 5.9mm. There are different bridge layouts, two base plates with varying dial-feet positions, and two slightly differing setting-lever springs. While the complete assignment of these differences to the FHF groups is not fully understood, comparing the corresponding calibres provides some insight. The Certina 12-11 movement falls within the FHF 1 to FHF 16 movement group, with individual designations starting from FHF 22. This movement offers stem wind and set functionality, a sub-second dial, and was commonly used around 1940.