GPS speedometers: Quickly collect GPS satellite speedometers, and satellites can be locked in real time. More precise than the OBD HUD, the GPS hud has the same operating logic as the speed radar. It has 100% versatility for all vehicles including cars, vans, off-road vehicles, trucks, trains, scooters, motorcycles, bicycles and boats. GPS HUD display :Driving speed, single driving time and mileage. When using it in a car, plug it into the car's USB port. If there is no USB port in the car, you need a car adapter or plug it into a power bank (not included). Overspeed alarm: The default vehicle speed setting is 120 km/h. When the overspeed alarm is active, it beeps 3 times to alert the car driver. Just press "up" or "down" to adjust it. If you want to disable the speed warning, just adjust the overspeed value to a very impossible high value. The display speed can be easily calibrated by hand. Do it 2-5 miles in advance to avoid quick tickets.