Real-time Tracking: See heart rate while you exercise.
Bluetooth Smart Technology: Bluetooth 4.0 capabilities connect the HRM to smartphones.
Built in memory gives you the freedom to train without a phone, capturing data and syncing it to your phone later.
Adjustable strap is surprisingly comfortable,the strap length is 25.6 inch-37.4 inch (65cm-95cm),can be adjusted to your size.
Third Party iPhone App Compatibility: Works seamlessly with over 50 iPhone Apps including Wahoo,Polar,Runkeeper, Strava, MapMyFitness, and Cyclemeter/Runmeter and select Android apps.