Arlen Ness, pre-filter for Monster Suckers without coverPre filter; also called a rain sock. Used for driving in adverse weather conditions; extreme rain etc. Engineered to add an extra layer of protection from water and other debris without restricting airflow. 100% monofilament polyester with a water repellent finish. Hydrophobic technology repels water in all weather conditions. Note: See 590443 for the optional rain sock used for Monster Suckers with cover.