Designed as a companion to any compatible fitness application, the Polar H6 Heart Rate Monitor Belt's physical connection to the wearer and subsequent transmittance of data via Bluetooth® ensure that it can be used around others without running the risk of suffering from interference. Plastic electrode areas on the reverse side of the strap directly contact the chest and detect heart rate, ensuring that data obtained by the device pertains solely to its wearer and nobody else - the connector then sends the heart rate signal to the receiving device. The Polar H6 heart rate sensor is compatible with Bluetooth® smart ready devices that support heart rate service. A separate application is required to view heart rate data on the receiving device (for example, a smartphone). If you have a polarpersonaltrainer.com account, Polar Beat automatically synchronizes your training files to it. Please note that you must sign in to your polarpersonaltrainer.com account when starting Polar Beat for the autosync to work. Battery levels are displayed on the receiving device if it supports a Bluetooth® battery service. Additionally, the device is water resistant though it must be noted that Bluetooth® wireless technology will not work in water.