Measure activity intensity with wrist based heart rate v237vosmart hr activity tracker uses elevate wrist heart rate technology178 to monitor heart rate at the wrist 247 that gives you the freedom to work out however you want with no additional heart rate strap needed using heart rate v237vosmart hr provides calories burned information whether youre going for a jog playing a game with friends or trying out a new boot camp class it quantifies the intensity of your fitness act