When I was a kid my old man had a military field alert type device, it was a small box about 4"x2"x2" and you put in a wire cartridge that looked about like a 35mm film case. The wire thickness was about the size of a hair and you wrapped the perimeter or whatever with the wire and if it was broken the box would either buzz or a small light would go off.

Anyone know the military designation or name for these "field type alarms"? Or possably a website that sells them?

Someone has got to know what these things are?

I found a shotgun shell alarm thing thats kinda neat but not exactly covert like the one im looking for.




http://www.hi-vel.com/Catalog__17/Perimeter_Alarm_Systems___Acce/hv_5.jpg