AP 6401

The in-house Calibre 6401 is a self-winding integrated chronograph movement designed for the 38 mm Royal Oak Chronograph. Operating at 4 Hz (28,800 vph), this 27 mm by 5.7 mm movement features 350 components, 44 jewels, and a 55-hour power reserve. It powers the hours, minutes, central seconds, date, and column-wheel chronograph, replacing previous modular movements with a fully integrated architecture visible through the sapphire caseback.