Polar H7 Bluetooth Smart Heart Rate Sensor Provides live, accurate heart rate to compatible mobile training apps, including Polar Beat Uses Bluetooth Smart technology providing ECG-accurate heart rate to any Bluetooth Smart ready device utilizing standard heart rate profile Compatible with iPhone 4S, iPhone 5, iPod touch (5th generation), iPad (3rd & 4th generation), iPad mini and iPod Nano (7th generation) User replaceable battery. For optimal battery life, detach transmitter from chest strap after every use Also uses Gym Link to connect with the majority of Polar heart rate monitors on the market and with compatible gym equipment Compatible with select devices using Android 4.3 or later (HTC: One, One M8, One Mini; LG: G2, Nexus 4, Nexus 5; Motorola: Moto G, Moto X; Samsung Galaxy: S3, S4 and S5, Note II, Note III; Sony: Xperia Z1