Omega Men's 3581.30.00 Speedmaster Broad Arrow GMT Automatic Chronometer Chronograph Watch Quality Swiss Automatic movement; Functions without a battery; Powers automatically with the movement of your arm Scratch-resistant sapphire crystal Case diameter: 44.25 mm Stainless-steel case; Silver-white dial; Date function; Chronograph functions; GMT function; Tachymeter function Water resistant to 330 feet (100 M): suitable for snorkeling, as well as swimming, but not diving