INDICATIONS: Hunter HEPAtech Air Purifier Replacement Filter: Easy Change Drop-in Filter Pack. Lasts up to 6 months under constant use.99.97% effective air cleaning. Captures smoke, pollen, dust, mold spores, pet dander and other irritating allergens. Three stage filter: Mesh particle screen prefilter captures larger particles such as dust, lint and hair. Submicron primary filter is made out of a micro-filter material which removes particles as small as 0.1 microns in size. Activated charcoal filter removes odors.