FLUSH PRO MARINE ENGINE FLUSHING AND WINTERIZING SYSTEM-VALVE ONLY FLUSHPRO™ VALVE MARINE ENGINE FLUSHING & WINTERIZING SYSTEM Flush your boat engine safely and easily. Transparent body allows visual inspection of water flow. Durable check valve system activated by water pressure from a garden hose & automatically shuts off hull intake when water pressure is applied. Adapter supplied with FlushPro™ makes winterizing easy. Constructed of plastic with SS spring. For inboard direct drive engine packages: P.C.M. MerCruiser 5.7 & above Indmar Jet Drive Volvo Penta Onboard generators. All ocean going systems with heat exchangers & Outdrives withut internal impeller pump. Made in USA.