Concertina razor wire fence

Concertina razor wire is named after the musical instrument, the concertina, due to its ability to expand and contract like an accordion. 

It is a type of security fencing wire constructed with sharp edges or points arranged at intervals along the strands. It This type of wire is used to prevent passage by humans and animals, often used in military or high-security environments to protect a perimeter. It is designed to inflict serious cuts on anyone attempting to climb through and therefore has a strong psychological deterrent effect.