Pentair Pentek GAC-BB Big Blue cartridges reduce unwanted tastes and odors, including chlorine taste and odor, from your drinking water for a cleaner, better-tasting result. Filled with granular activated carbon, each cartridge is designed for maximum contact between the water and the carbon to support optimal adsorption. Water enters one end and passes through the full length of the carbon bed before exiting the other end, while an internal expansion pad minimizes channeling and bypass. Before the water exits, a spun polypropylene post-filter helps reduce carbon fines and other suspended particles, and it is permanently fastened to a support basket to help eliminate bypass. The cartridge uses polystyrene end caps and outer casing and is rated for 40 to 125 degrees F. This heavy duty 9.75" x 4.5" cartridge fits 10-inch Big Blue and other compatible 10-inch heavy duty housings, making it a straightforward replacement for any 10" x 4.5" granular carbon cartridge. It reduces chlorine taste and odor for up to 12,500 gallons at 2.0 gpm. This is a pack of 8 cartridges.