CONCERTINA WIRE

Concertina wire, or Dannert wire, is a type of barbed wire or razor wire that is formed in large coils to be expanded like a concertina. In conjunction with plain barbed wire and steel pickets, it is most often used to form military-style wire obstacles. It is also used in non-military settings, such as when used in prison barriers, detention camps, riot control, smash and grab robberies in the U.S., or at international borders for security control.