When size matters: No matter which sport you choose, with the Suunto Smart Sensor - the smallest Bluetooth Smart compatible heart rate sensor on the market - you can measure your heart rate accurately and very comfortably. The sensor records your heart rate while swimming and transmits the data wirelessly to your Ambit3 watch or the Suunto Movescount app. By connecting the sensor to the free Suunto Movescount app, you can analyze, relive, and share your moves: Every move counts. The Suunto Smart Sensor comes with a newly designed heart rate belt, but it can also be used alone when attached to Movesense compatible sportswear.