MimoUSA License plate reverse backup sensor system is the first stylish 2 sensor license plate back up system on the market. Mounting 2 sensors on your rear or front license plate will ensure you the perfect safety and stress-free parking you have ever imagined. The sensors that are installed on the license plate frame send ultrasonic waves to detect obstacles in front or behind the vehicle. The controller receives the signal & transmits it to the LCD display inside your car.