Concertina Wire

        Concertina wire is a type of barbed wire or razor wire that is formed in large coils which can be expanded like a concertina. Each coil actually consists of two oppositely wound helices which support each other against crushing while allowing easy longitudinal movement.

        In conjunction with plain barbed wire and steel pickets, it is used to form military wire obstacles. During World War I soldiers manufactured concertina wire themselves, using ordinary barbed wire. Today it is factory made.