Runtastic Speed and Cadence Bike Sensor with Bluetooth Smart Technology Works with top-rated Runtastic Bike Apps turning your smartphone into a cycling computer Wirelessly measures biking speed and pedal cadence (rpm) for improved endurance and cycling performance Uses Bluetooth Smart and Bluetooth Smart Ready technology to connect to smartphones (long battery life) Easy to mount; mounting accessories included Compatible with iPhone 5s/5c/5, iPhone 4s and Bluetooth Smart Ready Android devices running Android 4.3 or more recent