Clasp knife attached to a piece of string, 1981 (c)

A clasp (or lock-blade) knife has a locking mechanism that locks the blade into its fully opened position. This lock must be released before the knife can be folded. The device improves safety by preventing accidental blade closure while cutting. This example was used by a soldier from 3rd Battalion, The Parachute Regiment, during the Falklands War of 1982.