The Garmin HRM Dual Heart Rate Chest Strap transmits real-time heart rate data via ANT+® and BLUETOOTH® Low Energy, giving you more options to train indoors, outdoors or even online. With the device, you'll consistently receive accurate heart rate data on your Garmin device, in online training apps like Zwift, or even on compatible fitness equipment during your workout at the gym. So no matter how you prefer to train, you'll get accurate, real-time heart rate data to help you reach new levels of performance.