Hardin Marine has developed this attractive, easy to use, quick connect thru-hull flushing system. These 316L stainless steel flushing thru-hulls allow the quick connection of a household garden hose to this fitting in mere seconds.  While the opposite end of the thru-hull features a 1/2" NPT female connection that can be connected into the inlet side of your cooling system or sea strainer.  When the garden hose is removed this unit looks like a simple thru hull yet has a spring loaded internal check valve.