The Cortebert 270 is a mechanical watch movement that was exclusively produced for Mido between 1935 and 1954. Its base plate is derived from the AS 1131/1132. The movement offers optional black rhodium plating and a pink-gold plated train. It features an Incastar regulator, which is the only large-scale produced regulator with a free oscillating hairspring. The spring is fixed between two rollers, allowing for length adjustment and eliminating isochronism errors caused by the gap between regulator pins. The Cortebert 270 movement incorporates functions such as automatic (bumper) winding, a sub-second display, Automatic function, and Incabloc shock protection.