Sten or Sten submachine gun, was a family of British 9mm submachine guns, used by Commonwealth forces during World War II and the Korean War. Its most notable features were its simple design and low production cost. The name STEN is an acronym derived from the names of the main designers of the weapon: Major Reginald Shepherd, Harold Turpin, and ENfield, the town where the Royal Small Arms Factory (RSAF) of London is located. Some four million Sten of various versions were made during the 1940s.
Sten Mark II was the most manufactured model, with about two million units. It was much simpler than the Mark I, without the wooden parts and the flash suppressor. It was shorter than the Mark I, the Mk.IIS (Mark 2 Silenced) version with a silencer was also produced.