a2aviator{at}gmail.com wrote:
> The foil can be defeated by taping the glass very heavily on the
> outside and most of the time it will not breach. A detector is more
> fail safe.
> 
> The other thing the detector affords is the ability to actually go off
> without a breach. It can detect the act of attempting to break the
> glass where the first hit may not penetrate. It can also monitor more
> than one pane. In a corner or placed at an angle with deflector behind
> it, the detector acts like a PZM microphone.

PZM!  I haven't heard that mentioned for years.  At one point, Crown Intl 
owned the patent and manufacturing rights for PZM.  Since I exited the audio 
field in the early 90s, I'm no longer sure what the status is on these gadgets.
--- SBBSecho 2.12-Win32