The MacNaught Max Flow M-DDP13PN-02 is a 1/2" polypropylene AODD (air-operated double-diaphragm) pump. It uses compressed air to drive two diaphragms back and forth to move liquid, and the Max Flow line also comes in aluminum, carbon-filled PVDF and tri-clamp stainless steel. Cal West Mashy represents MacNaught for Northern California and Western Nevada. Call 888-841-3335.