Rolex 3055

The engine of the Day-Date from the late 70s to late 80s, this COSC-certified caliber introduced the high-beat frequency (28,800 bph) and, most importantly, the “Single Quickset” date function to the line. While the day was not quickset, this movement was a major step in user convenience and powered the first sapphire-equipped Day-Date models (Ref. 180xx), setting the stage for its “Double Quickset” successor.