Features Tracking cadence data in real-time on your bike computer or smartphone with compatible training apps. Support to connect any BT5.0 or ANT+ enabled device and smart phones. Long battery life compatible for you.Normal use is up to 300 hours. IPX7 waterproof,no fear of water and rain.You can ride in tough weather conditions. Small size,light weight and no magnet design. Easily install on your bike's crank arm with the included rubber rings. Product incompatible for mation Battery: 1* CR2025 included Wireless transmission: BT5.0 ; ANT+/2.4G Working time: approx. 300 hrs Waterproof: IPX7 Shock resistance: 1.5m Natural Drop Size: 36 * 34 * 7.7 mm / 1.4 * 1.3 * 0.3 in Weight: approx. 7.8 g / 0.3 oz includes battery Warranty: 1 year HR40 Commodity Description With comcompatible for table fabric strap, and its slim, light and ergonomically in design. Meanwhile, The battery lifetime is 340 hours. HR40 supports the connection with bike computers or smart phones to sync real time heart rate data with cloud platcompatible for m compatible for analyzing training data, checking training effect, managing training plan and maintaining a good training state. Product specification Product size 59.8x35.3x11.9mm Net weight 47g Arm strap length 65~95cm Battery working time about 340 hours Waterproof IPX7 Transmission ANT+/BLE Heart rate range 40-240BPM