This product will let you know when to stop when trying to park in your garage. Simply remove from package, install batteries and mount it so that the sensor can read the front of your vehicle. Park your vehicle at least 2 feet away ( I set mine for 3) from the sensor and push the calibrate button. Now when you pull into or back into your garage the sensor will display green when it reads your vehicle and as you gradually get closer it will change to yellow and when you achieve where you set it the light will turn red.

Simple and effective.