The Honeywell FC100A1011 20"x20" Media AC Filter is a high efficiency Media Air Filter that can be used in Honeywell 20 x 20 Air Cleaners. This is a genuine Honeywell air conditioning filter. Honeywell FC100A1011 Specifications: * Nominal Size: 20" x 20" x 4 3/8" * Actual Size: 19 7/8" x 19 7/8" x 4 3/8" * MERV 10 Rating * Replaces FC35A1019 / 203721 * Fits Honeywell Series: F25, F35, F100, and F150 The Honeywell FC100A1010 20x20x5 utilizes Ultra-Web technology, which is exclusive to Honeywell High-Efficiency Media Air Cleaners. This air conditioner filter should be replaced at least once per year for maximum efficiency. Filter life based on air quality. PRICE IS FOR 1 FILTER, BUT BUY 2 AND SAVE MORE!