Ultrasonic parking sensors uses ultrasonic sound waves to measure distance, for example, from the bumper  of your car, to the car parked behind you, or to other nearby objects at the same height as the parking sensor.  When the preset minimum distance is crossed, an audible signal is generated to alert the driver.  Intended to assist the driver with the task of parking the vehicle, ultrasonic parking sensors are often found as standard equipment on modern luxury automobiles.

Now, using the ultrasonic parking sensor kit, you can retrofit any car or truck with ultrasonic parking sensors to aid you or someone you know with the task of parking their vehicle at lower cost.  This ultrasonic parking sensor is the answer you've been looking for.  Ultrasonic parking sensor stays mounted on the car, the system is automatically activated when reverse gear is engaged using 12v/DC from the reverse lamp (white bulb) to power-on the main unit, so it's always there to assist the driver with parking.  No matter where the vehicle travels, the ultrasonic parking sensor will be there to help safely park the car.