Audemars Piguet Royal Oak Men’s Watch 41MM Black Stainless Steel 15510ST. 50 m (5 ATM). Audemars Piguet Royal Oak is made perfect for any occasion. The 41 mm stainless steel case is assembled with a Grande Tapisserie dial and a water resistance of 164 feet. Powered by the self-winding 4302 calibre, this timepiece has a 70-hour power reserve.