This Pentek GS-10CAL/RO-B Inline Filter Cartridge Replacement is a 10" combination in-line filter composed of coconut shell granular activated carbon (GAC) and calcite. It can be utilized in various applications to correct low pH levels, polish water, brew better tasting coffee, tea, or other beverages (or in numerous other food service applications), as a post filter in many reverse osmosis systems, and more. It reduces the bad taste and odor of chlorine as well as sediment and increases the pH level of wa