This CAT Pump 5CP2120W pressure washing pump features concentric, high-density, polished, solid ceramic plungers for longevity and extended seal life. The manifold is made of a high tensile strength W770 alloy for continuous duty. The 100% wet seal design lets pumped liquids cool and lubricate on both sides. In addition, stainless steel valves, seats, and springs provide corrosion-resistance for a long life.