The Longines 4 is a lesser-known manual-wind version of the 0917 movement, which was specifically developed for Mido and utilizes the AS 1131/1132 base plate. Noteworthy features of this movement include a gold lever and the option of an Incastar regulator. The Incastar regulator is a unique large-scale produced regulator that incorporates a free oscillating hairspring fixed between two rollers to adjust its length and eliminate isochronism errors caused by the gap between regulator pins. The Longines 4 movement also includes functions such as manual winding and a sweep second hand. It was primarily used during the approximate period of 1950.