This filter is the pleated air filter replacement for the BMAC-20C air filter cabinet and measures 20” X 25” X 5”. The Lennox X0586 filter has a MERV 11 rating, which means that it filters out 85% of particles down to 3 microns. Filters Out: This includes – pollen, dust mites, mold spores, some bacteria, dust, smoke and more. This is a significant upgrade from a 1” furnace filter. This filter should be replaced every 9-12 months depending on the air quality in your home.