Hummingbird's GPS Speedometers provide a quick to install, vehicle-independent speed readout in vehicles that are not fitted with conventional speedometers.Using data received from the Global Positioning Satellite network the GPS Speedometer calculates three-dimensional ground speed and displays it on a clear to read digital display.This high technology solution eradicates the dependency on vehicle specific parameters, thereby reducing installation time and eradicating the need for periodic calibration.