Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Total junk

This thing is completely unreliable. I tried a variety of sensor heights and distances, and THREE DIFFERENT CARS. I moved everything else away from the sensor but the red light would not come on. I could have driven right through the wall without it telling me to stop.Apparently, based on the other reviews, a few people have gotten lucky, but there are also plenty of other people like me for whom it would not work at all. The odds aren't in your favor.