Audemars Piguet Royal Oak 4100SA Automatic 36mm. Description: 100% Authentic in Escellent condition. Case: Stainless Steel & Yellow Gold Bezel 36mm. Movement: Automatic caliber 2225. Dial: Gray dial, Hour Minute Date time. CRYSTAL / GLASS: Sapphire crystal. Bracelet/Strap: Steel & Yellow Gold with deployment buckle. Fits up to 7.5 inch.