9S7148 Rain Cap Assembly Fits Caterpillar PR-450C 3304 3306 3406B 3408 3408C 5"One New Aftermarket Replacement Rain Cap Assembly Fits Caterpillar (Fits CAT) Engines and Equipment This aftermarket replacement rain cap assembly mounts on the exhaust pipe outlet to prevent rainwater and debris from entering the exhaust system when the engine is not running. The spring loaded or gravity operated cap opens automatically under exhaust pressure and closes when the engine shuts down, protecting the exhaust stack from moisture and