Polar H7 heart rate sensor gives you live heart rate on your mobile training application, including the Polar Beat app, to make the most of every session. In addition to low energy Bluetooth smart technology, the H7 heart rate sensor uses Gym Link to connect with the majority of Polar heart rate monitors on the market and with compatible gym equipment. - HEART RATE MONITOR: Provides live, accurate heart rate to compatible mobile training apps through Bluetooth Smart technology - FITNESS TRACKER: Waterproof heart rate sensor compatible with all Apple iPhone, iPads, and Android Devices - STRONG BATTERY LIFE: For optimal battery life, detach transmitter from chest strap after every use - ADVANCED TECHNOLOGY: Gym Link connects Polar heart rate monitors and activity trackers with compatible gym equipment - CALORIE COUNTER CAPABILITIES: For those who want to count the calories they burn and get basic heart rate-based features to keep their fitness training simple - Out of package from buying in bulk, never used