Universal Car HUD Head Up Display Dual Chips Smart Digital Speed Meter HD LCD Display Plug and Play for All Cars, Buses and Trucks Features: Plug & Play: When connected to power, the HUD head up display car can work directly without any other operations. No skip speed, more consistent and smooth display. And a large font, clearly visible during the day and night. Widely used: Built-in GPS chip, car HUD head up display is suitable for all cars, buses, trucks, bicycles, scooters. Head-up displays driving speed Calculation and display of driving time and mileage Green data display, pleasing to the eye Speeding Alarm Setting Driving Fatigue Alarm View MPH or KM/h Automatic brightness adjustment via sensor for day and night driving Easy setup: connect power Play No professional installation required Specification: Unit: kilometer Material: ABSPC Color: As shown in the picture Size: 65.5*42.8*16mm So if you are testing at home or in the parking lot, perhaps the speed cannot be displayed correctly. Please test outside the vehicle with a good signal. Package includes: 1 x Head Up Display 1 x USB cable 1 x Sticker 1 x User Manual