
An RF detector, often sold as a hidden camera detector, picks up the radio signals that wireless cameras, audio bugs and GPS trackers transmit, and many models add a lens finder that makes camera lenses glint. Preppers carry one when traveling to sweep rental rooms and hotel rooms, and use it at home to check a car for trackers.
DRAFT: needs surplus category, related supplies (Flashlight, Pocket Flashlight, Faraday Bag), image and a voice pass. Linked from the hidden cameras concept with the anchor text hidden camera detector.