The RIPP Pre-Filter is a specially designed filter wrap made to help extend the service interval of your washable air filter when used in very dusty conditions. They are made from durable polyester material containing uniform micron openings. The Pre-Filter will stop small dirt particles without adding restriction to the intake. Durable double stitching will make sure the Pre-Filter will stay in place. These air prefilters are also coated with a hydrophobic coating to resist water to prevent water splashes from being ingested through the air filter.