The Osco 500 is a mechanical watch movement that shares similarities with the 1288, but features a larger base plate. It is commonly associated with the signature "1120" on the dial side, although it is unclear if this is always the case. Notable among other ETA movements such as the 1121, 1123, 1125, 1127, 1129, 1131, 1133, and 1139, the specific differences between these movements and the 1289 remain unknown. The Osco 500 movement is a manual wind movement with sub-second functionality and was commonly used in watches around the 1950s.