The Stefani 5 Micron 4.5" x 20 " cartridge is highly effective in reducing taste, odour, chlorine and sediment. The ultimate for beautiful drinking water. Suited for Stefani and other branded 4.5" x 20" Whole House Water Filtration systems. It is suggested you change your filter every 6 - 12 months. The cartridge is constructed from bonded activated carbon, offering superior treatment of water with no release of carbon fines. Carbon block cartridges are one of the most effective and widely used technology in the point of use water treatment industry today. Solid carbon block cartridges, or simply carbon blocks, are used either as standalone treatment methods or in a system with other cartridge types. Carbon is a very versatile and highly effective water treatment medium. It has immense surface area. Approximately half a kilogram of carbon contains a surface area of over 50 hectares (0.5 square kilometers). It is the best known treatment for organic chemicals, volatile organic chemicals, pesticides, herbicides, chlorine and its by-products. It is also an unchallenged taste-and-odor improver. When arranged in solid carbon or extruded carbon block format, it also provides very high quality particulate filtration, in some cases down into the submicron level.