The OH1 boasts an internal memory capable of storing up to 200 hours of heart rate training. Its 12 hour battery life also means it can accompany you on multiple workouts. Additionally, it's waterproof up to 30 metres and lets you follow your real-time heart rate data via the Polar Beat app, and third-party fitness software. If you're after an even more thorough breakdown of your activity, you can hook it up to the Polar Flow web service for extensive training guidance.

Most heart rate sensors are discrete in terms of appearance -- even if they're designed to be worn on your head. The same goes for the all-black OH1, which offers an adjustable strap, allowing you to position it on your forearm or upper arm. The heart rate sensor is available for pre-order right now, and will begin shipping in mid-September.