Polar H2 Heart Rate Sensor Track your heart rate and perform at your best with the Polar H2 Heart Rate Sensor. Not only does it measure your heart rate, it seamlessly adapts to your body shape so you can focus on your exercise. Soft textile material has a cloth-like feel to ensure comfort. Convenient hook allows you to put on/take off quickly. Slim design. New improved user-replaceable battery mechanism. 5kHz coded transmission, compatible with most Polar products and compatible gym equipment in fitness clubs.