This external air filter element is the primary intake filter for the engine. It removes airborne particulate from the combustion air stream before it reaches the turbocharger or intake manifold. The filter sits in the housing on the engine side of the intake system; a matching internal element is used in the same housing. A clogged element restricts airflow, causing a drop in engine power and increased fuel consumption. The manufacturer matches the original housing's sealing geometry, ensuring the gasket seats correctly to prevent unfiltered air from bypassing the element. On reinstall, ensure the housing is clean and the seal is properly seated.