KIS was the name of a Polish submachine gun from the time of the Second World War. It was designed and manufactured by engineers in Jan Piwnik's "Ponury" ("Grim") partisan group that was operating in Holy Cross Mountains region. The weapon was patterned after Sten, retaining its left-side magazine. Main differences were a longer barrel, with conical rear part, and lack of stock – the gun had a pistol grip instead.