Microphone pen

c. 1975

All Postal Inspectors are highly trained in the art of covert surveillance. Postal Inspectors use a wide range of technologies including hidden cameras, listening devices, recorders, and micro transmitters to help them observe and catch criminals. Although this recording devices appears primitive to standards in the 2000s, this equipment was quite sophisticated in the 1950s-1990s. This pen contained a hidden microphone used to secretly record the conversations of suspected criminals.