Sierra Marine 18-4458 Exhaust Protector Valve

Sierra 18-4458 Exhaust Flap. Fits 5" and 6" thru-hull exhaust outlets. Includes Stainless Steel clamp. Fits 6" outlet without modification, and also fits 5" outlet by removing a small, marked section at the bottom of the clamp portion. Heavy duty rubber flap valve helps to prevent water from surging into the exhaust system.