Mine is part of my clifford alarm, I got it from GAP security, cant remember exactly how much but I did haggle the guy down a bit. I think it was supposed to cost about £650 for all the options I chose but I ended up gettin it for about £400. It's just a sensor stuck on the inside of the windscreen behind the mirror, it must just create some sort of force field around the car You don't have to touch it like with some alarms just stand within about 6 inches of it It's funny as hell when people park next to it and you can see their confused faces wondering what the noise is, thinkin it's their own car. I saw a woman sit and open and close her door about 10 times before realising it wasn't her car making the noise