The Audemars Piguet Royal Oak Selfwinding Flying Tourbillon Extra-Thin (RD#3) 37mm (ref. 26660BC.ZZ.1356BC.01) is an automatic sport watch, with a 37mm 18-carat white gold case, powered by the 2968 movement and a 50-hour power reserve. Water resistance is rated to 50m, under a sapphire crystal.