Replacement Cartridge: 4FC-S Water Filter Cartridge, 4FC-S, (1) 4FC-S Fibredyne® II submicron carbon block cartridge, reduces cysts, chlorine, taste & odors, inhibits bacterial growth & scale, 15,000 gallons, 2.5 gpm, 0.2 micron, NSF 42 & 53 (EV969231)