This high quality after market cartridge is a compatible replacement which can be used with Selecto Scientific systems MF 620 and MF 5/620. Please note to purchase a quantity of 2 if using as replacements for the MF 620-2P or the MF 5/620-2P systems (the KWBGS-4520 is for the 2nd & 3rd stages) . Typically this cartridge is used as pre-filtration for fountain beverage machines and other commercial food service industry applications providing clear and great tasting water free from chlorine and chemicals. The carbon block cartridge will remove chlorine for 40,000 gallons through the process of adsorption. The KWBGS-4520 also provides 5 micron sediment filtration which entraps particles down to 5 micron furnishing crystal clear water. This sophisticated filtration will provide very high quality - great tasting water and will protect your beverage equipment from the potential adverse effects of unfiltered water. The reasonable cost makes this a very high quality - low cost alternative. Please note that replacement o rings are not included with this kit.