The ZPU (Russian: зенитная пулемётная установка, meaning "anti-aircraft machine gun mount") is a family of towed anti-aircraft gun based on the Soviet 14.5 mm KPV heavy machine gun. It entered service with the Soviet Union in 1949 and is used by over 50 countries worldwide. Quadruple- (ZPU-4) Double- (ZPU-2) and single-barreled (ZPU-1) versions of the weapon exist.