Perko Flush Pro Valve - 1"Flush Pro Valve 1" Finally! Freshwater flushing of your inboard is as simple as connecting a garden hose. Features: Polymer Stainless Steel Spring Flush your boat engine safely and easily Transparent body allows for visual inspection of water flow Durable check valve system activated by water pressure from a garden hose Check valve automatically shuts off hull intake when water pressure is applied Adapter supplied with Flush Pro make winterizing your