10″ x 4.5″ GAC Filters, Full-Flow Big Blue
These are Big Blue, full-flow 10″ x 4.5″ GAC filters by Pentek. They are constructed of granular activated carbon (GAC).
GAC is positively charged and, therefore, able to remove negative ions from the water such as ozone, chlorine, fluorides, and dissolved organic solutes by absorption into the activated carbon.