Requires minor installation. Install the electronic beam to cross behind your vehicle(s) such that the beam is behind the vehicle at the place where you want to stop each time you park. When the beam clears the vehicle(s) the red light on the wall ahead turns from red to green! A simple visual signal that assures you stop before contact ahead but after the back of your vehicle(s) clear so the door closes without contact. I think you may like this a great deal.