In street terms its called shatter rock around here. Many thiefs use it to break windows silently. It does'nt work well since it triggers the sensor for the alarm if you have a window mic. Although, I hear you run a good chance of preventing it if you put duct tape on the window. Supposedly it will keep it from shattering. Leaving a spidered window, pry it out with a screwdriver and pop, its out.

You once again won't get far because you have to defeat the other sensors.

Window tint works against you there too :(  (replaces the need for duct tape)

Worked on my car 2 years ago, alarm never sounded at all & they just pulled the pass window out after breaking it.

Actually had this happen to me a few years back,

I woke up, went to my truck and thought I left the window down. When I opened the door I saw the glass all over. The first thing I did was check my led diagnostic and realized my alarm had never gone off. They apparently broke the glass without triggering the shock sensor (which I had set sensitive). Must have crawled in after they broke it. Good news is the only thing they took was some CD's..you know the ones from columbia house that's like 12 for a penny. So no big financial loss other then a window.

What I did to prevent this was install an RF field disturbance detector. I figure nothing will stop them from breaking a window if they desire but I at least want my alarm to sound. It is very diffcult to enter the vehicle with that kind of sensor without sounding the alarm. Have had no problems since. I now do a few other "tricks" as well but for contents nothing beats a prox, IMO.