The Honeywell Universal True HEPA Replacement Filter is fully capable of capturing up to a staggering 99.97% of particles such as household dust, smoke, pollen, mold spores and pet dander. This package includes 1 HEPA filter and 1 gasket and is compatible with most Honeywell towers and tabletop air purifiers. It is recommended that each filter be replaced every 3 to 5 years for optimal use. Establish an unrivaled breathing experience for you and your loved ones with Honeywell and their second to none series of Filters. Captures up to 99.97% of airborne particles at 0.3 microns. Package includes 1 filter, which should be replaced every 3 to 5 years. For air purifier model 10500 (or HEPA filter no. 20500) two HRF-D1 filters are needed. For air purifier model 17000 (or HEPA filter no. 20500) two HRF-D1 filters are needed. For air purifier model 17005 (or HEPA filter no. 20500) two HRF-D1 filters are needed. For air purifier model 17352 (or HEPA filter no. 83154) two HRF-D1 filters are needed.