True HEPA filter, compatible with the Perfect Aire 1PAPUV27 air purifier. Captures 99.97% of all airborne particles as small as 0.3 microns such as bacteria, viruses, dust, dust mites, mildew, mold spores, pet dander and pollen. Package includes 1 activated carbon pre-filter to help reduce common household odors from pets, smoking and cooking. HEPA filter should be changed every 12 months and pre-filter should be changed every 3 months. Removal rate: CADR CFM, Smoke 143, Dust 145, Pollen 228. Type: HEPA Removal Rate: 99.97% Length: 5.83 In. Width: 18.66 In. Thickness: 1.1 In.