Razor Barbed Wire discription:

Barbed tape or razor wire is a mesh of metal strips with sharp edges whose purpose is to prevent passage by humans. The term "razor wire", through long usage, has generally been used to describe barbed tape products. While razor wire is much sharper than the standard barbed wire, it is named after its appearance, but is not actually razor sharp. However, the points are very sharp and made to rip and grab onto clothing and flesh.
The multiple blades of a razor wire fence are designed to inflict serious cuts on anyone attempting to climb through and therefore have a strong psychological deterrent effect. Razor wire is used in many high-security applications because, while it could be circumvented relatively quickly by humans with tools, penetrating a razor wire barrier without tools is very slow and difficult, giving security forces more time to respond. Razor wire contains a core hardened steel strip that is often under tension, so if cut, the recoil could cause the wire to unfurl and lash out, striking the cutter.

Like barbed wire, barbed tape is available as either straight wire or spiral concertina wire. Unlike barbed wire, which usually is available only as plain steel or galvanized, barbed tape is also manufactured in stainless steel, to prevent the points from rusting to bluntness. Typically the core wire is galvanized and the tape is stainless, although fully stainless barbed tape is used for expensive permanent installations or under water.
Barbed tape is also characterized by the shape of the barbs. Although there are no formal definitions, typically short barb barbed tape has barbs from 10 mm to 15 mm long, medium barb tape has barbs 20 mm to 25 mm long, and long barb tape has barbs from 60 to 66 mm long. There does not seem to be much available research to indicate whether longer barbs are actually more effective in resisting penetration, but they provide a stronger psychological deterrent.