The Girard Perregaux 31.9 is a significant watch movement developed jointly by Hamilton-Buren, Breitling, and Heuer during the period of 1969 and onwards. It incorporates the Dubois-Depraz 8510 module, which is installed on a modified Buren 1281 base. This movement features a crown positioned at 9 o'clock, a micro rotor, and a double excenter regulator for curb pins and stud carrier. With an indirectly driven minute hand, it allows for a low profile design. The Girard Perregaux 31.9 boasts several functions including an automatic chronograph with 60-second, 30-minute, and 12-hour measurements, cam switching capabilities, date setting by changing 21-24 hours, automatic winding, Incabloc Shock Protection, and a calendar. It has been utilized since 1969.