?Warranty?First time usage, it takes 10-30 seconds to get GPS signal, and it can't work indoor. If the HUD device is faulty, no need spend time to return it to , just contact with us to ship you a new HUD directly. You are welcome at anytime. ?On/Off automatically? Built in vibration sensor, when detect car motion, it will be on and display the driving speed in big fonts; if keep stationary 100% for more than 3 minutes, it will be off. When it's off, no power consumption at all. ?Install?Easy install and use, no buttons, no need any setting, no need read manual, USB Cable plug and play. If your car has a USB port, pls plug the USB cable to USB port; if your car doesn't have a USB port, then give it a car adaptor. ?GPS Speedometer?Collects the speed data from GPS satellites, no relation with car engine, no destroy to car circuit board or OBD port, and can be widely used on SUV ATV Pick-up Truck Scooter Golf Cart Bus Boat Train Bike Motorcycle… can work on all vehicles on the market. ?Head Up Display?HUD display, it has only one function - display the driving speed. Compared to normal LED HUD on market, it doesn't need paste any project film on car glass, and it doesn't have double image even under terrible sunshine at noon.