Electrostatically charged Filtrete fibers work like magnets to remove 92% of dust, pollen, and mold. They effectively remove particles as small as 3 microns of smoke and pet dander making them 20 times more effective than ordinary furnace/air conditioner filters. Carries a 1000 MPR (Microparticle Performance Rating). Each provides 3 months of protection under normal conditions. MERV 11. Red label.