The OCATO Bluetooth 4.0 wireless heart rate sensor is a portable device Worn on the chest to monitor your heart rate during workouts. It can be Adjusted to fit most chest sizes through a convenient soft strap. Your Heart rate is transmitted to a compatible device with the Micoach\Runtastic\RunKeeper APP through Bluetooth Smart (Bluetooth V4.0) Wireless technology. More accurate and efficient than most wrist Monitors, the OCATO Bluetooth 4.0 monitor can be used for measuring Your heart's performance in nearly any physical activity: Jogging, Running, cycling, even swimming! By monitoring your heart rate, you Can adapt your workout to strengthen your cardiovascular system, Increase stamina, burn fat or adhere to rehab restrictions. No adapter Necessary, as all data is shared wirelessly via Bluetooth technology - up to 10 meters/33 feet away!