The Polar H7 heart rate sensor helps transmit heart rate data seamlessly via Bluetooth connectivity. The chest worn sensor provides real time, accurate heart rate data, even while swimming. The H7 is compatible with numerous other Polar devices including the FT7 Fitness Watch and Polar Loop. It's compatible with iPhone 4S and later, and with selected Android devices including Samsung Galaxy S3 and S4 using Android 4.3 or later. The H7 is compatible with the Polar Beat health app, as well as various third party apps.