Outerwears K&N Pre-Filter Rc-0880 Developed specifically to upgrade the protection your K&N enhanced filter element already offers. Crafted from silicone-impregnated micro-mesh for water resistance and meticulously dielectrically welded at the seams, these pre-filters have the ability to eliminate particles as tiny as .005 in diameter without causing any significant restriction in the airflow to your engine. The material features consistent micron-sized openings that enable air to pass through while effectively filtering out undesired particles such as sand, dirt, clay, and moisture. Features: Dyno and flow bench testing reveals no loss of horsepower or airflow when using this product Keeps your engine safer in harsh conditions Filters particles down to .005