Invicta Men's 4550 Subaqua Noma III Collection 7751 Automatic Chronograph Watch Quality Automatic movement; Functions without a battery; Powers automatically with the movement of your arm Scratch-resistant-sapphire crystal Case diameter: 50 mm Black-ionic-plated-stainless-steel case; Dark-gray dial; Day-date-month-and-moon-phase functions; Chronograph functions Water-resistant to 1640 feet (500 M)