Description: These reusable K&N Filtercharger air filters outflow any other filter--up to 900 cfm--for power gains of up to 15 HP. They use a surgical cotton fabric soaked in oil as their tack barrier. Sandwiched between an aluminum screen wire, the holes in the cotton catch tumbling air and straighten it out. Since air moving in a straight line flows faster, the filter actually improves airflow. They can be covered by up to 1/4 in. of debris before air restriction makes cleaning necessary. The filters come pre-oiled, and many are available as a direct fit for your application.