Audemars Piguet Perpetual Calendar

Audemars Piguet's Royal Oak Perpetual Calendar 26674ST.OO.1320ST.01 measures 41 mm across in stainless steel, with a case thickness of 4.1 mm. The blue dial sits under a sapphire crystal and reads clearly against the tone-on-tone finish. Inside is the self-winding calibre 7138, a Manufacture movement adjusted solely through the crown. The watch carries a full perpetual calendar, showing date, month and weekday, and adds an astronomical moon phase display. This combination of functions runs without needing correction until the next century turnover. An integrated steel bracelet closes with an AP folding clasp. The case holds a water resistance rating of 50 metres.