
If you are looking for a replacement/alternative for Honeywell #FC100A1037 this is NOT what you are looking for . This filter is 3 5/8 inches thick while the Honeywell filter is 4 3/8 inches thick. Instead, you'll want the Nordic Pure 20x20x5 - it's the same dimensions: 19 7/8 x 24 7/8 x 4 3/8 as Honeywell. The 20 x 25 x 4 labeling is misleading or at least allows regular homeowners (as opposed to HVAC technicians) to end up ordering the wrong product. Also, out of the four orders I've ordered the Nordic Pure, twice the shipping box and the filters it contained were severely damaged. Yes, Revain/Nordic Pure "got it right" but it was still a hassle. Those issues aside, these are good filters that come at a good price, which is why I keep ordering them. The advertised Air-Handler filter size is 20 x 20 x 4, but the standard Honeywell filter is too thick for this, and the Nordic Pure fits just right. Find out. Review Carbon filter Nordic Pure 20x25x4 MERV 12 Pleated Plus for AC ovens, 2 packs