Replacement media #FC100A1011 for Honeywell Model F100F1020, FC35A1019 [20x20]This is BETTER than the Honeywell as their's is a MERV 10 product (MERV-11 Universal Cartridge)
The filter incorporates 100% synthetic fibers that are electrostatically charged, thermally bonded and manufactured in an engineered gradient structure. No modification to the filter frame is necessary. Each filter is sealed in plastic to avoid contamination before use.