All you need is an interior motion sensor to attach to any aftermarket alarm, I have one on mine vert, well I had one. The basic concept is that when you arm the car with the top down, and then some jerk off sticks his hand in your car, your alarm goes off. Great idea, in theory, but the reality of the situation is that the motion sensors sense changes in the air, so on humid days, or days where the humidity changes rapidly, the alarm will go off! Its really frustrating, I had one on my vert for like 6 months, but I couldnt take the falsing anymore so I pulled it out. If you dont mind your car falsing all the time, then go ahead and get one, but in my opinion, dont waste the money, hey but if you want one, I have it sitting in a desk drawer, and I am more than willing to get rid of it.