The BioLogic Bluetooth Smart Heart Rate Strap transmits heart rate data wirelessly to compatible apps in real-time so you can keep track of your workout without need of a dongle or adapter. It works with Bluetooth Smart Ready devices, including iPhone 4S and above, and other smartphones. The super energy efficient transmitter runs for approximately 200 hours on one battery. The electrodes are built into the soft and comfortable, washable strap for accurate measurement.