This Comet Regulator # 1204.0564.00 is compatible with the Comet APS31, APS41 and APS41AP Diaphragm Pumps. It is a pump mounted control with adjustable pressure knob and manual dump lever. Max. Flow: 15 gpm. Max. Pressure: 580 psi. Ports: two 3/8" ball valve outlets, 1/2" hose barb bypass.