This Carbon Filter (2-Pack) is designed for use in Vornado True HEPA Air Purifiers. Replace your carbon prefilter every 4-6 months with continuous use, depending on your environment. The activated coconut carbon prefilter traps odors and other organic compounds. It also extends the life of the HEPA filter by trapping larger particles. Maintain the health and comfort of you and your family. Contains 2 filters. This Carbon Filter, part number MD1-0023, works with Vornado air purifier models AC300 and AC500.