The Polar WearLink transmitter with Bluetooth wireless technology picks up your hearts signals and transfers that data into a compatible mobile training application, The soft fabric chest strap seamlessly adapts to your Body shape, bringing full freedom of movement to your training, With its hook mechanism, the transmitter is just as quick to put on as it is to take off, Provides heart rate information to compatible mobile training applications, Uses Bluetooth transmission, ensuring that the mobile device finds your heart rate signal, Washable fabric strap, Waterresistant connector, User replaceable battery, Anti bacterial, Size: MXXL, Dimensions: 8L x 1W x 5H, SKU: SPTMN4643