1. Head Up Display shows the driving speed only. Compared with typical LED HUDs, it does not require applying a projection film to the windshield and it avoids double-image glare in bright sun. 2. GPS Speedometer uses GPS data to show speed. It is not linked to the engine, so it will not affect car circuits or the OBD port. It works on a wide range of vehicles including SUV, ATV, pickup, scooter, golf cart, bus, boat, train, bike, motorcycle, and more. 3. Install is USB plug-and-play. No buttons, no settings, no manual required. If your car has a USB port, plug in via USB; if not, use a car adaptor. 4. On/Off automatically. Built-in vibration sensor turns the display on when motion is detected and shows the speed in large font; if the vehicle remains stationary for more than 3 minutes, it powers off to save power. 5. Use scenarios - Fleet or rental vehicles: speed readout without windshield films or vehicle modification. - Motorcycles, scooters, bikes: GPS-based speed display without wiring to the engine. - Cars, boats, golf carts, buses, ATVs: convenient speed display across diverse vehicles without altering electronics.