Razor wire is a mesh of metal strips with razor edges whose purpose it is to prevent passage by human beings. The sharp edges of the wire can cause serious cuts in any person attempting to pass through. Razor wire supplanted barbed wire which was sufficient to prevent the passage of animals such as cattle but which could easily be circumvented by humans. Razor wire is typically found outside of prisons and some long term mental hospitals (to keep people in) and around military installations (to keep people out). Razor wire is often made out of a ribbon of stainless steel.