The booby-trap Alarm Signaling Device signals you when trespassers are present on your property. This popular and versatile perimeter security device may look like an ugly duckling, but it works beautifully. It can be deployed across paths and entryways, attached to doors or gates, etc. This re-usable device is activated by a trip wire, which fires a 12 gauge signal. A 12 gauge blank is included (replacement blanks are also available). Includes mounting hardware. Trip wire available below. Not shippable by Air.