The Pentek, Ametek, US Filter C8 Carbon Impregnated Cellulose Cartridge filters chlorine taste & odor, bad taste & odor, and sediment from your drinking water. The C8 has a high dirt-holding capacity and can be used in a wide variety of applications. The Pentek C8 is also a direct replacement for the Keystone 900. Filter capacity depends on usage and water quality. If you notice an increased flow rate or any taste & odor returning to your water this may be a sign that your filter needs to be changed.