Boost your cycling performance with our cadence and cycling speed sensors: find out what your most efficient pedaling rate is and measure your speed and distance accurately. The sensors included in this set work with Bluetooth® Smart technology and consume very little power. You can later analyze your training in the Polar Flow web service. Sync your speed and cadence sensor set with your smartphone.- Small and light design with firm bike attachment- Compatible with iPhone 4S and later, and with selected Android devices including Samsung Galaxy S3 and S4 using Android 4.3 or later. Check all compatible devices