Air filter. Captures 90% of large allergens like mold spores and pet dander from the air passing through the filter and also microscopic allergens like dust, smoke, smog, particle bacteria and particles that can carry viruses. Lasts 3 months. Meets the "American Lung Association Health House Indoor Air Quality Guidelines". No unnecessary antimicrobial chemicals added. "Filtrete" filtering material will not support the growth of bacteria, mold, mildew or fungi in normal use.