Garmin vivosmart

vívosmart HR smart activity tracker with wrist-based heart rate.It  measures heart rate at the wrist 24/7. That gives you the freedom to work out with no additional heart rate strap needed. Using heart rate, vívosmart HR provides calories burned information & quantifies the intensity of your fitness activities, providing better credit for your efforts. You can even use your vívosmart HR as a heart rate strap on your wrist when paired with other compatible Garmin devices.