Double Diaphragm Air Pump PII.50 Chemical Industrial Polypropylene 1/2" or 3/4" NPT Inlet/Outlet Double Diaphragm Air Pump PII.50 Chemical Industrial Polypropylene 1/2" or 3/4" NPT Polypropylene with Santoprene Diaphragms included Connection: 1/2" or 3/4" NPT Good abrasion resistance, chemical resistance, and heat resistance Ideal for use with low viscosity petroleum fluids