Switching out a pump hasn't been easier with this fully plumbed Pressure Pro CAT Pressure Washer Pump 4000PSI (SLP66DX40-408). This pump installs easily with four bolts and comes complete with an unloader/regulator, water inlet fitting w/filter, easy start valve, thermal relief valve and oil. It has a 1" hollow shaft and is designed for direct mounting to a gas engine. An internal pressure unloader protects the pump, while solid ceramic plungers run cooler and extend the life of the pump.