The ZPU-4 is a towed quadruple barreled anti-aircraft gun based on the Soviet KPV 14.5 mm machine gun. It entered service with the Soviet Union in 1949 and is used by over 50 countries worldwide. Double and single barreled version of the weapon exist - called the ZPU-2 and ZPU-1 respectively.
Development of the ZPU-2 and ZPU-4 began in 1945, with development of the ZPU-1 starting in 1947. All three were accepted into service in 1949. Improved optical predicting gunsights were developed for the system in the 1950s.
