The Audemars Piguet Royal Oak Perpetual Calendar 41 Stainless Steel (Ref. 26574ST.OO.1220ST.03) features a 41mm stainless steel case housing the self-winding Caliber 5134 movement, offering a 40-hour power reserve. Its blue dial with "Grande Tapisserie" pattern displays day, date, month, leap year, and moonphase indicators. The watch is water-resistant up to 20 meters and comes with a stainless steel bracelet.