The Cortebert 537 watch movement, which was in production from 1939 to 1942, features a Breguet hairspring and a coupling mechanism facilitated by a swiveling hand pinion. This movement holds the distinction of being the smallest diameter for a serial-produced chronograph during its time. Its functions include a manual-wind chronograph with a 60-second hand and a pillar wheel, as well as a sub-second feature.