The STEN was a British submachine gun used during World War II. It was a simple and inexpensive weapon that was mass-produced and widely used by British and Commonwealth forces. The STEN was a blowback-operated, magazine-fed machine gun that fired from an open bolt. It was designed to be easily manufactured and was made of stamped steel parts and a wooden stock. It was reliable and accurate, and could fire up to 500 rounds per minute.