How does it work? -GPS Odometer Speed Sender provides a reliable calibration-free replacement for mechanical speed senders.-Using data received from the Global Positioning Satellite network, the GPS Speed Sender calculates three dimensional ground speed and provides a pulsed output compatible with existing mechanical speed senders. -This high-technology solution eradicates the dependency on vehicle specific parameters thereby reducing installation time and eradicating the need forperiodic calibration.Welcome to my store, I will show you high-quality products, I hope you can buy the right products, I wish you a happy shopping.