HQRP Filter 4-Pack for Hamilton Beach TrueAir 04712 04381 Allergen Reducer 840117900 True-Air O4712 O4381 Coaster HQRP&reg; Four Filters plus HQRP&reg; Coaster; Replacement filter for 210 square foot room; For optimum performance, replace the filter every 2 - 3 months; The maximum durability is 120 days; Effective at capturing dust / dust mite debris, mold spores, pollen, smoke and pet dander; Compatible with Original filter. 2 weeks DOA replacement warranty!