Ramair filters owe much of their dirt retaining properties to the unique advanced polymer treatment with which they are impregnated during manufacture. They can be given a new lease of life when they become heavily soiled by cleaning them thoroughly with Ramair polymer solvent cleaner and applying fresh Treatment to the foam filter material. Please Note: Ramair Filters Treatment is more advanced than ordinary filter oil. Using any other product may reduce the effectiveness of your filter and may affect the warranty. Ramair polymer solvent cleaner is: NON TOXIC NON-CORROSIVE 100% ORGANIC BIODEGRADABLE Economy cleaning kit (CK-001) includes 1x 100ml cleaner, 1x 100ml Ramair advanced treatment in bottles, set of rubber gloves and instructions on cleaning and best re-application.