Limits maximum pump discharge pressure. Opens quickly; maintains pressure within close limits. Adjustable 60-180 psi or 100-300 psi. Pilot-operated main valve. Pressure setting is adjustable with single screw. Factory tested and pre-set to your requirements. UL listed and factory mutual approved for both split-case centrifugal and vertical turbine pumps. Sizes: 3 to 8 inches. Material: Ductile iron ASTM A536-epoxy coated, cast steel ASTM A216 WCB - epoxy coated and also available in some other materials.