Gee Whiz - does this mean I could defeat these things by carrying a small EMF pulse generator, such as an electric butane BBQ starter wand? ;-) CIAO - Martin. Martin R. Green mrgreen@NOSPAMbigfoot.com To reply, remove the NOSPAM from the return address. Stamp out SPAM everywhere!!! ================= Actually, they are deactivated by a pulse that "burns them open"...something a B-B-Q starter would be hard pressed to produce;^)) Simply covering the patch with a piece of aluminum foil will render it inoperative. -Cheers, Hank