The MacNaught Max Flow M-DDP19AN-02 is a 3/4" aluminum AODD (air-operated double-diaphragm) pump. Compressed air drives two diaphragms back and forth to move liquid. The Max Flow line runs from 1/2" to 3" in polypropylene, aluminum, carbon-filled PVDF and tri-clamp stainless steel. Cal West Mashy represents MacNaught for Northern California and Western Nevada. Call 888-841-3335.