The K&N PreCharger is a specially designed filter wrapmade to extend the service interval of your K&N Filtercharger when used in very dusty conditions. They are made from durable polyester material containing a uniform weave. The PreCharger will stop small dirt particles with minimal restriction to the airflow of the filter. The PreCharger is designed to be run dry and canbe cleaned with K&N Filter Cleaner. The PreCharger is custom made to fit each application. Double stitched elastic openings assure that the PreCharger will stay in place. The PreChargers are available in a variety of colors, all with a silk-screened K&N PreCharger logo.