Pentair Pentek GAC-BB Big Blue Carbon Water Filter, 10-Inch, Whole House Heavy Duty Granular Activated Carbon (GAC) Replacement Cartridge, 10" x 4.5", reduces bad taste & odors to provide good general purpose drinking water. It fits all 10" Pentair Pentek Big Blue or other 10" heavy duty housings and can replace any 10" x 4.5" carbon filter cartridge. It has post-filter that helps reduce carbon fines and other suspended particles from the filtered water. It is NSF International tested and certified for your peace of mind. It has 12,500 gallon capacity and can be replaced every three months or when you notice a drop in water pressure or water quality.