This 3M furnace filter measures 12 in. x 24 in. x 1 in. and is made of fibreglass. This filter was designed to purify the air by capturing airborne microparticles, including smoke and smog, as well as airborne allergens such as pet dander, pollen, and mould spores. It can also get rid of big particles like lint and dust. This filter lasts 3 months. Plus, this product meets the American Lung Association Health House Indoor Air Quality Guidelines (MERV 11 - 1000 Microparticle Performance Rating). No unnecessary antimicrobial chemicals were added. Moreover, its filtering material won't support the growth of bacteria, mould, mildew, or fungi during normal use.