Adjustable 22mm silicone strap fits up to 8-inch wrist circumference; lightweight alloy 45mm round case Color touchscreen display with customizable watch face; easy-to-use app available for iOS and Android Make & receive calls with built-in speaker; receive notifications for Facebook, WhatsApp, email, text Optical heart rate monitor sleep & activity tracker (steps, calories & distance) Recharge battery with micro-USB cable Part Number TW5M31600SO Item Shape Round Dial window material type Mineral Display Type Digital Clasp Buckle Case material Metal Case diameter 13.5 millimeters Case Thickness 45 millimeters Band Material Silicone Band size Unisex Band width 22 millimeters Band Color Gray Dial color Black Bezel material Metal Bezel function Stationary Calendar Day-Date-Month-Year Item weight 2.4 Ounces Movement touch-screen