Outerwears K&N Pre-Filter Ru-3780 Upgrade the protection of your engine by adding an intake pre-filter from Outerwears specifically crafted to match your specific K&N upgraded filter element. These pre-filters are constructed from silicone-impregnated micro-mesh, providing water resistance and are dielectrically welded at the seams. They effectively eliminate particles as small as .005 in diameter while maintaining optimal airflow to your engine. The material features uniform micron-sized openings that permit air to pass through while filtering out undesirable 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