This is a direct-drive triplex (three plunger rods) plunger pump, constructed of a brass manifold, easy-to-service 304SS stacked valve assemblies, solid ceramic plungers and standard NBR (Buna-N)seals and o-rings. The 4SPX pumps offer high quality and exceptional life for the portable pressure washer market. The 4SPX is a flanged, hollow-shafted pump designed to bolt directly onto a gas engine drive, providing easy, compact installation. The 4SPX pump comes standard with a Integral Regulating Unloader with built-in By-Pass and fixed Chemical Injector that mounts onto the unloader. Technical Specifications Max Flow 3.2 gpm / 12.1 lpm Max Pressure 3000 Inlet Port Size 3/8" NPT(F) Discharge Port Size 3/8" NPT(M) RPM 3450 Drive Type(s) Direct Material Brass