Holmes Tower Air Purifier with Permanent Filter This Holmes Tower HEPA-Type Air Purifier removes up to 99% of airborne particles as small as 2 microns from the air that passes through the filter Slim tower-style filter takes up less space in your home while freshening the air Permanent filter never needs replacing; simply vacuum it regularly to keep it clean Optional push-button ionizer helps remove particles Washable pre-filter captures large particles and extends the life of the filter