Air filters are critical engine components situated between the air intake and throttle body, preventing abrasive particulate matter from entering the engine. Constructed typically of pleated cellulose or synthetic media, they provide a large surface area for maximizing airflow while trapping contaminants as small as 5 microns. Filter efficiency is rated by percentage of particle capture, influencing engine performance and longevity. Variations include paper, cotton gauze, and non-woven synthetic materials, each offering differing airflow and filtration balances. Proper sealing via gasket or mounting interface is essential to prevent unfiltered air bypass.