Park Zone provides a solution for parking for people who have difficulty with depth perception. The product installs with just 4 screws and 4 batteries. NO POWER PLUG! Which makes even nicer you can put it anywhere you dont have an outlet!! You park your vehicle in the desired location inside the garage, press the button on the top of the unit, and the system is ready. Park Zone will tell you when your vehicle is about 8 ft. from the wall by illuminating a yellow light. When you reach the desired distance, the red light visually indicates that it's time to stop.