Long Life Main Filter for CT 11, 22, 33, 44 and 55 Dust Extractor. Measured in microns, wood dust is particularly troublesome to remove from an environment once it is airborne. Eliminate the majority of the dust created at the source before it is ever released into your environment. Cloth based Long life Filter features a special 'M' fold to prevent build up. Tough fabric is more wear resistant when the scrubber handle is used. Every other fold is shorter, easily allowing dust to shake out when the handle is pulled. Designed to trap particles down to 1 micron while maintaining airflow, allowing you to reach full capacity without clogging or caking.