The 3M™ CUNO® legacy drop-in style replacement cartridge for ice maker Applications, model CFS420IMF, when used in a drop-in style filtration housing, provides consistent quality water by reducing particulate. The built-in scale inhibitor helps to reduce potential harmful effects of scale build-up on equipment. Our 3M™ CUNO® legacy drop-in style replacement cartridge for ice maker Applications, model CFS420IMF provides consistent quality water by reducing particulate and scale. The built-in scale inhibitor helps to reduce the potential harmful effects of scale build-up on your equipment. This replacement cartridge features a graded density design and is compatible with drop-in style filtration housings. 3M™ water filtration products systems and cartridges offer a wide range of solutions designed to address many types of water quality concerns. Third party certifications, such as NSF and WQA are an advantage provided on many 3M™ water filtration Products. 3M™ purification is a known leader in filtration technology recognized for innovation, trust and quality around the world.