The 3M CFS420IMF is a replacement cartridge that purifies sediments from drinking water. The 3M CFS420IMF replacement cartridge comes with a built-in scale inhibitor to combat scaling in pipes and kitchen appliances. The cartridge is rated for 5-micron filtration. It has a granular activated carbon—one of the best options to get the assurance of holistically purified drinking water. The activated carbon absorbs the impurities. It is great for supplying ice machines that receive hard water.