Long-range locator
A long-range locator is a class of fraudulent devices purported to be a type of metal detector, supposedly able to detect a variety of substances, including gold, drugs and explosives; most are said to operate on a principle of resonance with the material being detected. == Theory of operation == Skeptics have examined the internals of many such devices and found those that have been examined to be incapable of operating as advertised, and have dismissed them as overpriced dowsing rods or similarly useless devices.