The Longines 507 watch movement, exclusively produced for Mido during the period of 1954-1960, features a base plate derived from the AS 1131/1132 movement. It offers optional black rhodium plating and can incorporate either the Fonto regulator with a mobile stud carrier and adjustable regulator pin-width or the Incastar regulator. The Incastar regulator is the only widely produced regulator that employs a free oscillating hairspring, where the end of the spring is secured between two rollers to adjust its actual length, eliminating isochronism error resulting from the gap between the regulator pins. This movement provides automatic winding and sweep seconds functions.