Kuryakyn 9335 Pre Filter/Rain Sock Kuryakyn uses only K&N and aFe oiled gauze filters in their air cleaners which, when properly maintained, are water repellent. Even so, there may be times you wish you had a pre-filter to keep bugs, dirt, wash water, or torrential downpour out of your air cleaner. Made exclusively for Kuryakyn in the U.S.A. by Outerwears. Water repellent, UV-resistant and filters debris down to 0.005".