The Rolex 1535 watch movement is an automatic movement with two roller freewheels and a ball-bearing rotor. It features a worm screw regulation gear and is based on the manual wind calibre AS 1687/1688. The automatic mechanism was jointly developed by Doxa, Eberhard, Favre-Leuba, Girard-Perregaux, and Zodiac. The specific differences between the 42.2 and 42.3 variants are not known. It has several functions, including automatic winding, a sweep second hand, date display set by changing 20:40-24h, and a hack feature. This movement was commonly used around 1965.