Three functions: combined in one filter -- H13 True HEPA and Carbon filter plus separate pre-filter filter to capture larger particulate to help extend life of subsequent filters. Reusable pre-filters are washable and can be cleaned as needed. H13 True HEPA filtration captures up to 99.95% of particles as small as 0.1 microns, including allergens, pollen, dust, pet dander and smoke. Long-lasting performance up to two-years (depending on usage conditions).