Fresh Water Booster System - This unit is used to transfer water from a fresh water tank to any machine. The bladder collapses under the pump pressure and then feeds that pressure back to the machine. This keeps the pump from running as often, and eliminates constant cycling that is normally seen with a pump on its own. This is a plus with any machine that uses a manual or "toilet bowl style" float valve for incoming water. Self Priming - Installs in convenient location; floor or wall. Can run dry with harm if water supply fails. 4.5 GPM/40 psi.