Honeywell HRF-D1 Long Life True HEPA Replacement Filter D1 Type: HEPA Filter Used For: Air Purifier Allergen Reduction: Yes Feature: The Honeywell Universal True HEPA Replacement Filter captures up to 99.97% of particles such as household dust, smoke, pollen, mold spores and pet dander*. This universal filter is designed to replace Honeywell True HEPA filter numbers 20500 and 20590. ***For air purifier model 17000 (or HEPA filter no. 20500) two HRF-D1 filters are needed.*** Captures up to 99.97% of airborne particles at 0.3 microns. Replace every 3-5 years as needed. Fits models 50100, 10500, 17000, 17005, 10590. For air purifier model 17000 (or HEPA filter no. 20500) two HRF-D1 filters are needed Each HRF-D1 contains 1 HEPA filter and 1 gasket. Fits most Honeywell towers and tabletop air purifiers.