The Zenith 400 watch movement is a result of collaboration between Hamilton-Buren, Breitling, and Heuer. It incorporates the Dubois-Depraz 8510 module, which is mounted on a modified Buren 1281 base. The movement features a crown positioned at 9 o'clock, a micro rotor, and a double excenter regulator for curb pins and stud carrier. The indirectly driven minute hand enables a low profile design. This movement supports various functions, including an automatic chronograph with 60-second, 30-minute, and 12-hour counters, cam switched operation. Additionally, it includes a date display that is set by changing the 21-24-hour time. The Zenith 400 movement was primarily used around 1972.