K&N® AIR FILTER WRAP These filter wraps work to prolong the life of your K&N FilterCharger when used in extremely dusty conditions. The durable polyester material contains uniform micron openings that stop all dirt debris .005 or larger, yet airflow is not restricted. This pre-filter will also prevent splashes of water or mud from saturating your K&N air filter. Please be aware this material is water repellent, not water proof These may be cleaned with soap and water.