The International Durowe 1977-4 is an open face calibre pocket watch movement available in options including a bimetallic screw balance and a Breguet hairspring. It was manufactured in sizes ranging from 18.5 to 19''', with heights varying from 4.2 to 5.9mm. There are different bridge layouts, two base plates with differing dial-feet positions, and two slightly differing setting-lever springs. The movement is grouped under FHF 1 to FHF 16, with individual designations starting from FHF 22. The specific assignment of these differences to the FHF groups and calibres is partially known. The International Durowe 1977-4 movement features stem winding and setting, sub-second display, and was commonly used around 1940.