The trip wire early detection systems offered for sale are made of 6061-T6 billet aluminum. Each comes with removable ground spike with screws for mounting. Uses readily available 209 shotgun primers. Used by state and federal agencies as trip wires/booby traps during exercises. Great for keeping bears and other wildlife away from trashcans and gardens, early warning devices for your property or anywhere else you need to have notice of trespassers.