Osculati protecting end cover for through hull exhaust outlets, made from tough rubber. The flap acts as a check valve to help prevent sea water entering the exhaust outlet and flowing towards the engine. Without a flap, water can easily flow into the exhaust line when the boat is stopping or travelling slowly.

The Osculati exhaust flap is adjustable to two different sizes. A stainless steel hose clip is also supplied, which can adjust to secure the exhaust flap whether it is at standard size or cut size.