Polar Bluetooth Stride Sensor Includes smart features to measure your running speed and distance when paired with a Bluetooth Smart ready device and a mobile training app such as Polar Beat Running watch is ideal for running on a treadmill, indoor track, or on the muddiest trail After your workout, view and analyze your running cadence and stride length on polarpersonaltrainer.com, our free online training diary Small, shock and waterproof sensor fits firmly onto your shoelaces to handle even the most demanding runs Compatible with Bluetooth smart ready mobile devices and certain training apps, such as Polar Beat; Note: not compatible with Polar monitors