KDF/GAC Water Filter Cartridge For Undercounter Units - Removes Chlorine Lead Heavy Metals Lasts 12,000 Gallons! Removes Chlorine, Lead, Chemicals, Heavy Metals. Leaves beneficial minerals, such as calcium and magnesium, intact. Rated to treat 12,000 gallons (depending on water quality) Fits any industry-standard housing using 9 3/4" cartridges Includes chlorine test strips to verify when it's time to replace cartridge.