Powering the uncommon ceramic model is the Audemars Piguet caliber 5134, with the incredibly thin 4.5mm mechanism being seen in a number of previous iterations of the Royal Oak Perpetual Calendar. True to its name, the 40-hour automatic movement ensures a perpetual calendar functionality for the watch, which together with the dial, showcases the current week, day, date, astronomical moon, month, leap year, hours, and minutes continuously.