Vktech L18 IP54 Bluetooth Smart Bracelet watch BT4.0 Blood Pressure Heart Rate Fatigue State Tracker for Android iOS Phones Wrist Strap Material DowCorning TPSiV Metal Face Material Magnesium Aluminum Alloy Adjustable Wrist Strap Length 157mm ~ 205mm Alloy Body Shell Material Polycarbonate Battery Capacity 41 mAh