Replacement filter compatible with Therapure TPP640 Tower Air Purifier Filtration removes up to 99.97% of airborne particles as small as 0.3 microns in size including smoke, dust, pollen, pet dander, mold spores and dust mites Foam gasket seal for high performance filtration directs air through the filter and keeps air from escaping around the sides Recommended to replace every six (6) months, or more often in harsh environments, for maximum efficiency Package contains two (2) filters Filter-Monster branded replacement compatible with Therapure TPP640 filter removes smoke, dust, pollen, pet dander, mold spores, and dust mites from the air. Compatible with Envion Therapure TPP640 Tower Air Purifier.