This external air filter element is the primary intake filter for the engine air system. It captures airborne particulate before the air reaches the inner safety element and the intake manifold. The filter sits in the housing mounted on the engine; its pleated media provides the surface area needed to maintain airflow while trapping debris. A clogged outer element restricts engine breathing, causing a drop in power and an increase in fuel consumption. The manufacturer specifies a matching inner filter for the housing; both elements should be replaced together to maintain the seal between the stages. On installation, ensure the housing is clean and the gasket seats evenly to prevent bypass leakage.