H400 Head Up Display Projector Car Speedometer Universal Auto HUD GPS Detector OBD2H400 Head Up Display Projector Car Speedometer Universal Auto HUD GPS Detector OBD2 Features: HUD short for Head Up Display,the main function is to display the car dashboard information (e. g. speed,RPM,water temperature,voltage,trip distance, etc),and keeps the driver's eye always on road to avoid the dangerous of lowering down head to read the dashboard Stereoscopic image formation, clear, no double image, no doesn't need any reflective film