APEX RF-1020 Filter Cartridge Granular activated carbon (GAC) is a proven option to remove organic chemicals, odors or tastes to water such as hydrogen sulfide (rotten eggs odor) & chlorine. KDF-55 filter media effectively remove chlorine and heavy metals and control microorganisms NSF approved, acid washed, high performance coconut shell activated carbon. High chemical absorption capacity. Perfect solution for household of any size. Easy installation. Filter effectively removes hundreds of contaminants from water. Designed to be used in most standard sized housings.