Life Fitness Soft Strap and Heart Rate Monitor Watch Combo Bluetooth 4.0 Connectivity for Smartphones / 5 KHz transmission connects to watches and cardio equipment. Continuous EKG Accurate Heart Rate from Strap / On-Demand EKG Accurate Heart Rate by touching Stainless Steel Top Case. Can be used with and compantible Bluetooth 4.0 device and application No recharge required