Polar CADENCE Sensor BLE USA Improves your cycling technique and identifies your optimal cadence Measures the real-time and average pedaling rate of your ride Interference-free data lets you evaluate and analyze your individual performance more accurately Small and light design with firm bike attachment, Uses Bluetooth low energy wireless technology Compatible with Polar V800, Polar V650, popular cycling apps, the iPhone 4S and later and select Android devices using Android 4.3 or later