Keep your air purifier operating at peak performance. Filter captures up to 99.97% of airborne particles and microscopic allergens. Replacement media must be used with pre-filer: HRF-AP1. For best performance, replace once each year Filter Type: HEPA Filtration For: Allergens Dust Mold Spores Pet Dander Pollen Smoke Air Cleaner Compatibility: Honeywell HPA100, HPA200, HPA300 Width: 6 3/4".