Hummingbird Electronics' GPS Speed Switch provides a simple to install, calibration free speed based switch.Speed thresholds are set using internal switches in either km/h or mi/h.Using data received from the Global Positioning Satellite network, the GPS Speed Switch calculates three-dimensional ground speed. If the speed exceeds the threshold, relay contacts switch, providing the installer with maximum versatility.This high technology solution eradicates the dependency on vehicle specific parameters, thereby reducing installation time and eradicating the need for periodic calibration.