20-Pack of Alen HEPA-OdorCell FiltersDesigned for T100/T300, the Alen HEPA-OdorCell Filter combines three layers of filter technology to purify the air in your home while destroying heavy odors at a molecular level. Contains 20 filters. Polluted air first passes through Alen's washable Pre-Filter to capture large particles, extending the life of the filter. In the second layer, air moves through a unique, electrostatically charged HEPA type material that attracts and captures dust, pollen, pet dander, mold spores and other airborne pollutants. In the final layer, clean air passes through hundreds of cells filled with Alen's patented Molecular Conversion Powder where tough odors like tobacco smoke are destroyed at a molecular level, leaving the air smelling fresh and pure.Note: The Alen T300 HEPA Air Purifier requires two (2) filters. The Alen T100 HEPA Air Purifier requires only one.