21.5X27.5 Media Air Filter-MERV 10 Media Air Cleaner Replacement Filter Single pack of the Honeywell FC100A1045 MERV 11 Pleated Filter 21.5" x 27.5" x 4". Brand new, genuine Honeywell product. Replacement filter for the Whole House Electronic Air Cleaner F200, F100, F150, F35, F25, F27. Replace the filter every 6 to 12 months. Filter measures 21.5" x 27.5" x 4" Since 1885 Honeywell has been providing customers with cuttingedge technology in the home comfort industry. From the first thermostat to todays innovative Indoor Air Quality products, Honeywell continues to be a leader in the home comfort market.