This Honeywell U HEPA-Type Filter helps capture the following airborne particles: dust, pollen, pet dander, dust debris and smoke and more.* The built-in carbon pre-filter captures larger airborne particles and activated carbon reduces unpleasant smells.* To ensure efficiency and performance, it’s important to replace HEPA-type filters 3x per year. This Honeywell HEPA-Type Filter is designed exclusively to fit Honeywell Air Purifier models HHT270 and HHT290 Series.A Honeywell Air Purifier with a Honeywell Certified filter will filter and circulate air up to 4.8 times an hour in the stated room size.** If you have pets or stale indoor air, air purifiers help deliver cleaner, fresher air. Always purchase Genuine Honeywell replacement air purifier filters. They are certified to help capture unpleasant smells and the following microscopic particles: dust, pollen, pet dander, dust debris, and smoke and more.* Other compatible filter replacements are not certified to offer the same performance or efficiency. Disclaimers: * From the air that passes through the filter, 2 microns and larger.** Based on 3rd party independent CADR testing for the smoke CADR value when operated at the highest level. Air circulation depends on many factors, such as room size and configuration. All of the air in a room may not pass through the filter.