Crimestopper Backup Collision Avoidance System with 4 Flush Mount Sensors - The Backstopper™ system helps avoid collisions while backing up. Perfect for RVs, Vans, Motor Homes, the Backstopper automatically searches for any obstacles in the path of your vehicle and displays the distance to the object on a 2-digit LCD and bargraph display. Tri-tone audible alert also keeps you informed. Includes 4 flush-mount sensors, hookup wiring and display module.