Entry level 20X20" media air cleaner, 4" extended media. F100F media air cleaner captures significant amount of airborne particles in air circulated through unit. Recommended as basic minimum air quality product. Includes; cabinet, access door and FC100A pleated media filter. High efficiency media filter captures particles as small as 0.3 microns. Applicable to all gas, oil and electric forced air furnaces and to compressor cooling up to 5 tons. Mounts in the return air duct. Rugged zinc-coated, roll-formed cabinet resists corrosion and can support weight of residential furnace and evaporator coil. Requires no electrical connections. Mounts in any position. Requires no maintenance except periodic media filter replacement. Quick and easy media filter replacement. Easy upgrade to higher performing media or electronic air cleaner.