Men's Automatic Watch | 40 mm Open-Heart | Stainless Steel Bracelet | Self-Winding MechanicalThe Men's Open Heart Automatic Watch from Smith Watches is a 40 mm mechanical timepiece with a cut out dial at 9 o'clock that exposes the beating balance wheel, a 316L stainless steel case, and a stainless steel bracelet. Self winding automatic movement, approx. 40 hour power reserve, 3 ATM water resistant, 2 year warranty. What is an open heart watch? An open heart watch is a mechanical watch with a small cut out in the dial that exposes the balance