Thing (listening device)

Thing (listening device)

The Thing, also known as the Great Seal bug, was one of the first covert listening devices (or "bugs") to use passive techniques to transmit an audio signal. Because it was passive, being energized and activated by electromagnetic energy from an outside source, it is considered a predecessor of current RFID technology.

• http://en.wikipedia.org/wiki/Thing (listening device)
• Page 87 - Kyle, C., McEwen, S., and DeFelice, J., 2012, American Sniper: The Autobiography of the Most Lethal Sniper in U.S. Military History: HarperCollins, New York, 289p.