Permatron activated carbon filters, package of 4 filters. One year supply, replace 4 times a year. Designed specifically to fit all 20" x 20" F50F, F300. The F50F, F300 have a prefilter slot and a post-filter slot. One Permatron carbon filter slides in to the post-filter slot. The carbon filters are the full size of the air cleaner and not split in pairs like the original Honeywell prefilters. Each panel measures exactly 19-15/16 x 19-7/8 x 5/16. This postfilter kit fits the Honeywell: F300E1027 F50F1032 F300A2020
Permatron's activated carbon absorbs odors and fumes. Whereas the collector cell captures particulate, the carbon captures noxious gasses. Permatron charcoal filters exceed manufacturer specs with 14 grams of carbon per square foot along with a low 0.06 wg air resistance. The carbon is finely ground resulting in over a million square feet of surface area. The carbon is impregnated into the filter media and heat set. There are no loose granules, the filter can be rinsed or vacuumed. Vapors are pulled by molecular action in to tiny pores and held. In manufacturing the carbon, the activation process creates millions of micropores. The pores are sized and formulated to remove common household VOC's.
Permatron prefilters and carbon filters are constructed with a rugged galvanized steel frame. The frames do not easily kink or push out of square. They are not flimsy like the Honeywell brand. The prefilter polypropylene weave is gripped solid by the steel frame. Very good quality.
Permatron filters are made in Illinois. The foam, activated carbon, poly-propylene, aluminum mesh and steel frame are all products of the USA.
The genuine Honeywell prefilters are stamped with Product of Mexico.