Copied from motocrossactionmag: "IT NOT ONLY TELLS YOU HOW MUCH TIME ON YOUR ENGINE, BUT ALSO HOW HIGH YOU REVVED IT ON THE LAST LAP. Not only will it work as a regular hour meter, that gets it powers and information from the pulsing of the spark plug, but it will measure the highest rpm you achieved during a moto (up to 16,000 rpm). It is resettable so that you can check rpm by the lap, moto or life cycle."