Works as advertised. Easy to install and calibrate.  Red light comes on when my vehicle is in the exact spot where it was when I calibrated the unit, which is the whole point.  My last unit had a switch where you could select the distance where the red light came on.  Choices were 1', 2' or 3'.  This unit is much better at letting you know precisely where you want to stop.  All you have to do is mount the unit to the wall, park your vehicle exactly where you want it, turn the unit off, then turn it on.  Calibration takes a few seconds, then it's done.