This Hypro GS40GI Regulator (9910-GS40GI) is a control unit designed to mount on Hypro D30 and D50 diaphragm pumps. The Hypro GS40GI Regulator comes with the following: Pressure gauge, bypass lever, adjustable high pressure relief valve, two 1/2" hose barb outlets with individual shut-offs, and a 3/4" hose barb bypass. NOTE: You cannot use diaphragm pumps without regulators. Every diaphragm will require the use of a pressure regulator.