For Use with Oiled Filters #  5117 , # 5117D , #  5118 , #  5122 , #  5124 , #  5151 Volant Pre-Filters are factory treated using a proprietary hydrophobic process and are manufactured from the same durable polyester material as their race proven regular style. This unique material contains uniform micron openings that will filter out debris .005 or larger. This pre-filter will prevent splashes of water, mud and sand from saturating your air filter.