The Speedometer gauge with TFT Screen, it display the range clearly. 9-32VDC Working Voltage, Speed Meter Gauge is IP67 waterproof and anti-fogging protection. | Diamete: Open a 85mm (3 3/8") and 55mm( 2 3/16”) depth hole to put the gauge into it, easy to install. | Three unit can be switched: km/h; mph; knot;(rounded to one decimals). GPS Speedometer fit for car, tractor, truck, boat, marine, motorcycle etc. | GPS SOG: Speed Over Ground: 0-600km/h; ODO: odometer: 0-999999km (can be adjusted by the back button.); TRIP: 0-999.9km (Return Zero When off electricity.); COG: Course Over Ground (Orientation Pointer) | After connection, it takes about 30 seconds to get signal in the first time. It gets quicker under a clear view of the sky.