Replacement 4-Filter Set for Ivation IVAHEPA01 True HEPA Air Purifier. Each set includes 1 True HEPA Filter, 1 Charcoal Filter, and 2 Carbon Filters. Carbon filter absorbs unwanted fumes/vapors, Charcoal filter eliminates bad odors, HEPA filter captures tiny particles as small as.5 microns. Suggested replacing Carbon filter every 3 months, HEPA and Charcoal filters every 6 months. By LifeSupplyUSA.