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