Alwaysfresh High Capacity Commercial Water Filter Cartridge, Certified by WQA Gold Seal NSF/ANSI std 42 & 53 for chlorine, taste, odors, turbidity, cysts, 1 micron filtration, 20,000 gallon capacity, 1.67 gpm flow. Independently Tested for Chloramine Reduction for 3000 gallons! Also approved in Canada: CSA B483.1 Filter protection by Antimicrobial Silver Zeolite ions. Change cartridge every 6 months for optimum performance. Also great solution for Clear Cube ice machines for Residential Applications