Water Resistant Pre-Filter(Black) for (FPE-34133) Fleece 2nd Gen Swap Air Filter Our Fleece Pre-filters are specially designed to extend the service interval of your air filter when used in heavy dust conditions. Made from a durable polyester material it will stop small dirt particles with minimal restriction to the airflow of the filter. Pre-filters are available in either black or orange and come with a silk-screened Fleece logo.