DESC: Jabsco's Par-Max Series of automatic pressure pumps are for use with fresh water systems. The Par-Max 3 provides up to 3 outlets with 3.5 GPM of water flow. The Par-Max 4 provides up to 4 outlets with 4.3 GPM of water flow. When the pressure in the water system drops below 20 PSI, the pumps automatically turn on, bringing the pressure back up to 40 PSI to keep the water flowing. Both pumps feature a four chamber diaphragm design that is self-priming and can be run dry without any danger of damage. Specifically designed to provide super quiet, ultra smooth flow, the pumps' features include vibration and shock reducing bumpers, battery conserving low amperage motors, and corrosion proof bases and marine grade components. 1/2'' hose barbed and 1/2'' threaded snap in ports included with each pump.