Key features: Switch on automatically when reverse gear is engaged 2/4 sensors design The LED Screen should be mounted on rear roof of the car Digital, acoustic, vision and direction alert Mirror reflection type. All digits showing on the LED screen will be reflected on the original rearview mirror. Embedded installation, Technical data: Working Voltage: 10~ 15 V Max. Power: 3.6W Working temperature: - 35℃~ + 70 ℃ Detecting distance: 0.1 m ~ 1.5 m Measuring error: ?.05 m Sensor detection angle: 60 ? Alarming Volume of built-in Siren: 80dB Alarming Volume of external Siren: 80dB Response Time: 250 ms Ultrasonic Frequency: 40KHz Current Consumption: 240~300 mA