Honeywell CF200A1008/E 4 3/8-Inch Ultra Efficiency Air Cleaner Filter MERV 12 rating for up to 60 times more efficient than typical 1-inch fiber glass filter Easily fits Aprilaire/Space-Gard models 2200 and 2252 Captures high percentage of house hold airborne particles, including microscopic particles you can't see No time consuming assembly required. Lasts up to 12-months 16 x 25 x 4.5-Inch