The ETA 390 watch movement, produced around 1945, is a manual wind movement that features a sweep second hand. It is similar to the 1090, 1091, and 1190 movements, with differences between them remaining unknown. Notably, the 1191 movement incorporates an Incastar regulator with a free oscillating hairspring, where the spring is fixed between two rollers to adjust its length and eliminate isochronism error caused by the gap between regulator pins.