Wahoo Trackr Heart Rate Monitor Accurate, reliable, comfortable and connected, the Wahoo Trackr Heart Rate monitor offers athletes everything they need from a heart rate sensor to take their performance to the next level. Key Features Strap Length: Adjustable from 27" to 36" (68cm to 91cm) Maximum Chest: Fits up to 50" (127cm) chests Connectivity: ANT+ and up to three Bluetooth connections Supported Devices: iOS - iPhone, iPad, Mac, Android devices, Windows Battery: Rechargeable Lithium Ion Battery Life: Over 100 Active Hours