Outerwears K&N Pre-Filter Ru-1750 Developed specifically to upgrade the protection your K&N enhanced filter element already offers. Crafted from silicone-impregnated micro-mesh for water resistance and dielectrically welded at the seams, these pre-filters excel at capturing particles as minuscule as .005 in diameter while maintaining optimal airflow to your engine. The material features consistent micron-sized apertures that permit airflow while effectively screening out undesired elements like 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