Concealment devices, as the term suggests, are used to hide things for the purpose of secrecy.

Examples in espionage include dead drop spikes for transferring items to other people, and hollowed-out coins or teeth for concealing suicide pills.

Examples in smuggling include suitcases with false bottoms for hiding contraband.

The picture shows a hollow container, fashioned to look like an Eisenhower dollar, which is still used today to hide and send messages or film without being detected. Because it resembles ordinary pocket change, it is virtually undetectable as a concealment device (although if a hollow coin is suspected, it can be easily confirmed by weighing against a normal coin on a simple balance). Such hollow coins were created from two ordinary coins, by milling out one face and the interior of both coins (to create a cavity), and the edges of one (so it could slide into the other). The half coin with intact edges would also have a pin-prick size hole drilled through its face, so the device could be opened by inserting a pin. A scratch may be added to help line up the faces while closing it—although it is very difficult to detect a slight misalignment by casual inspection. A device of this nature was famously discovered by a paper boy in the "Hollow Nickel Case".

During World War II, a British organisation called MI9 was responsible for creating many concealment devices for "escape aids" to assist prisoners of war to escape.