Permatron activated carbon filters, package of 4 filters. One year supply, replace 4 times a year.
Designed specifically for the White-Rodgers or Electro-Air 20 x 21 air cleaner. Each filter measures 20-5/16 x 21 x 5/16". These carbon filters are for all SST1600, SST16, 16C26S-xxx, 16C27S-xxx, 20C28S-xxx, UST.
These filters are the full size of the air cleaner and not split in pairs like the original White-Rodgers filters. One permatron carbon filter replaces a pair of the F825-0468carbon filters.
These Permatron carbon filters simply side right in.