K&N Air Filter Cleaner is the only cleaner recommended to clean K&N cotton air filter elements. The 99-0606 Air Filter Cleaner will bring your K&N oiled cotton air filter to like new condition. K&N Power Kleen works to dissolve the dirt build up and old filter oil, and can be washed away with water. The use of other cleaning solutions can void the air filter's warranty. It is so good at cleaning greasy dirt and grime that it can also be used as an industrial strength degreaser. Part 99-0606 is a 12 ounce pump bottle of Power Kleen.