The Polar H9 is an affordable heart rate sensor made as a complementary device for other fitness trackers, smartwatches, and applications. The H9 can comfortably be strapped on the user’s chest while working out- even while swimming, since it is waterproof for up to 30 meters. This device can easily be linked to various fitness devices and applications that lack a precise heart rate sensor for a more picture of the user’s workout.