The 90028 has stainless steel pistons for improved seal life and features a stainless steel integrated unloader with our easy-start system. To ensure compatibility, be sure to match engine orientation, PSI, GPM, engine shaft diameter, and current pump inlet and outlet connection Standard Connections: This replacement pump features a garden hose inlet and threaded M22 connection high pressure hose outlet; Use it with many pressure washer hoses, including Simpson MorFlex models 40224, 40225, 40226 and Santoprene model 41182 Skip the Oil Change: This pump features a maintenance-free crankcase so you never have to change the oil; It is manufactured from fully anodized die-cast aluminum for protection against corrosion; Use it for years with your pressure washer accessories Extended durability: A Thermal Relief Valve (TRV) protects the pump from overheating while in bypass mode; The TRV releases small amounts of hot water and intakes cooler water to prevent overheating and extend the life of the pump.