The Osco 50 watch movement is a manual wind movement with a sweep second function. It is equivalent to other calibers such as Aurore-Villeret 120, Bulova 6AH, and FHF 120, along with their respective variants. The movement shares design details with Bulova calibers and is believed to have originated from Aurore-Villeret. The differences between calibers 120-1, 123-1, and 212 are not known, possibly indicating variations in plate shapes. The Osco 50 movement was commonly used around the year 1945.