I just purchased the GE 5150 shock sensors a few weeks ago. They are closed loop, so you can just stick the two wires in the external terminals of DS12A's or hot-wire them to DS10A's and they just work. During shock, the sensor/loop is opened for a few seconds and then closes again.
They are tiny, you stick them on the windows with the supplied adhesive tape and they have no batteries as they are powered by piezo-electric (movement/vibration). I bought them for pretty cheap off of ebay, I think they cost $9 each or something like that. They are also available through several retailers including on Amazon if you do a google search.
The best part with the DS12A is that the external terminals act as a secondary sensor with different codes and the SC1200 registers it as a different sensor. So I have one DS12A per window that handles both the window opening, and glass breakage individually.
I also set up macros through AHP so that whenever the glass break sensors are tripped (whether the alarm is armed or not) I receive a text message on my cell phone. (Same with the smoke detector but that's a story for a different thread)
