PA VB35 Controlsets Unloader Valves. Pressure regulating unloader valve complete with metallic intake manifold. At gun shut off, the water flow is bypassed at reduced pressure. Direct fitting to the pump by means of two hollow screws. Sturdy steel and brass construction. Adjustable locknut to control the max pressure. Easy maintenance. Hexagonal shaped check valve to avoid jamming. Possibility to fit a venturi injector, on delivery, for chemicals. Plastic knob, upon request.