Pressure regulating valve adjusts pressure. AR Bolt On Unloader AR 20400 Fits: SRCV, XRV, XMV -- 3.5GPM To 4.5GPM -- SXMV, RK, RKA, RKV Up To 4000PSI.This unloader features a bolt on design with internal by-pass system. Adjustable pressure releases pressure in pump head when in by-pass, protecting from over pressurization. Eliminates by-pass hose and fittings and includes a fixed or adjustable built-in chemical injector. The molded plastic adjusting knob is designed for user comfort. Brass body with a stainless steel, plunger and spring, by-pass is aluminum or brass.

Works from 2500PSI to 4000PSI.