Holmes Single Pack 99.97% True HEPA Air Purification "B" Filter: * True HEPA filtration * Helps remove up to 99.97% of airborne allergens as small as 0.3 microns from air passing through the filter * Particles of that size include grass and tree pollens, household dust, pet dander, mold spores, and smoke * For use with Holmes Allergen Remover models HAP633, HAP726 and HAP8650 * Contains 1 filter per pack