The Longines 561.1 watch movement was jointly developed in the period 1969- by Hamilton-Buren, Breitling, and Heuer. It incorporates the Dubois-Depraz 8510 module 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 allows for a low profile. The Longines 561.1 movement offers various functions, including an automatic chronograph with a 60-second, 30-minute, and 12-hour cam-switched system. It also includes a date function that can be set by changing the 21-24 hour markers. This movement is automatic and includes a calendar feature. It has been in use since 1969.