Razor wire, or concertina wire, is a high-security fencing material made from galvanized or stainless steel with razor-sharp barbs designed to deter and obstruct intrusion. Typically, a single 10m roll covers a 450mm–730mm diameter area, often installed on top of walls or fences. It is exceptionally difficult to cut with standard tools, making it ideal for prisons, military, and commercial security, often paired with electric fences.