Omega Men's 3523.80.00 Speedmaster Day-Date Automatic Chronograph Watch Quality Swiss Automatic movement; Functions without a battery; Powers automatically with the movement of your arm Scratch-resistant sapphire crystal with anti-reflective treatment inside Case diameter: 39 mm Stainless-steel case; Blue dial; Day-date function; Chronograph functions; Tachymeter function Water resistant to 165 feet (50 M): suitable for swimming and showering