Patek Philippe · Automatic

240 Q

The perpetual calendar built on the 240, and the movement behind Patek's first self-winding perpetual calendar with moon phase — the reference 3940 of 1985. The calendar works sit as a module over the ultra-thin base, and the whole assembly still measures 3.75 mm. Thinness is the point: a perpetual calendar is normally a thick watch, and the 3940 established that it did not have to be.