The Hypro Control Unit GR40 is used on two different Hypro Diaphragm Pumps, the D403 and the D303. This Regulator includes high pressure relief valves, an easy-to-read large pressure gauge, a complete bypass lever and two 1/2" outlets. The two outlets have individual shut offs for easy operation. The GR40 has a maximum flow of 11 GPM and a maximum operating pressure of 580 PSI.