Air filter. 20 in. x 24 in. x 1 in. Captures airborne microparticles including smoke and smog airborne allergens, pollen, pet dander and mold spores besides large particles like dust and lint. Lasts 3 months. Meets the "American Lung Association Health House Indoor Air Quality Guidelines". 1,000 Microparticle Performance Rating (MERV 11). No unnecessary antimicrobial chemicals added. "Filtrete" filtering material will not support the growth of bacteria, mold, mildew or fungi in normal use.