Protect your boat water system appliances and pump from damaging pressure of unregulated marina water hookups. Reduce high water pressures (up to 100 PSI [6.9 BAR] down to 35 PSI [2.4 BAR]). Built-In backflow preventer. Easy to install. Easy-clean in-line filter. Two models: a permanently installed flush mount model and in-line model with brass garden hose fittings that connect dockside water entry and garden hose water hookup.