It uses precision biometrics to measure blood flow and calculate hyper-accurate heart rate measurements, allowing you to track your fitness data.The comfortable design allows you to wear it on your bicep, tricep or forearm - no more restrictive chest straps! The battery lasts up to 24 hours and the armband boasts a 100ft range with dual-mode connectivity to Bluetooth and ANT+ devices.Onboard Memory up to 13 hours of training time (ANT+ FIT file transfer)Bluetooth Low Energy / ANT+ Connection24 Hour Battery Life5 Heart Rate Zone IndicationsSuperior accuracy with all skin tonesIP68 Waterproof Rating