The Strava app supports most Bluetooth Low Energy (BTLE) and ANT+ heart rate monitors, depending on your phone's compatibility. Please check the specifications for your phone. Bluetooth Low Energy compatibility is usually available for iPhone 4S and Android version 4.3 and above. ANT+ compatibility is built-in for specific Android models and available for iPhone or Android with a separate ANT+ adapter accessory. For more information and instructions, see our articles on connecting sensors on iPhone and Android.