Hoover filter bags type A allergen filtration fits all hoover canister cleaners using type A bags， it traps 100 percent of dust mites and their eggs and 99.98 percent of ragweed and common grass pollens. The electrostatically charged liner enhances the capture of extremely fine particles. Ideal for many with allergic or dust related discomforts. ALLERGEN FILTRATION: Traps over 99% of dust and allergen matter down to 5 microns including household dust， dust mite debris， grass and ragweed pollen.