Audemars Piguet Royal Oak Perpetual Calendar (25829STOO0944ST01) self – winding automatic watch, features a 39mm stainless steel case surrounding a skeleton dial on a stainless steel bracelet with folding buckle. Functions include hours, minutes, day, date, month and moon phase. This watch comes wit the Certificate of Authenticity. F Serial. We back this watch with a 2-Year WatchBox warranty!