The Wahoo Cadence RPM sensor is a slim and small cadence meter. The sensor is easy to assemble on your bike. You dont need to fumble with magnets, because this system doesn't use a magnet. The dual-band technology gives the data on your smartphone and ANT+ bike computer. The Wahoo Fitness RPM works through bluetooth smart, also called bluetooth 4.0. A highly energy-efficient method of communication. Use the Wahoo Cadence RPM sensor to workout with your iPhone(4S and up), ipad (3 and up) or android (4.3 and up) smartphones. Display your cadence easily in almost every bike app. Collecting data about cadance has never been easier.