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.