Pentair Pentek CFB-Plus Series Cartridges are modified molded block cartridges built with Fibredyne technology and bonded powdered activated carbon (PAC). The CFB-Plus 20BB is a Big Blue cartridge that reduces chlorine taste and odor and bad taste and odor for cleaner, better-tasting water, with a nominal 5 to 10 micron rating suited to whole house, food service, commercial, and industrial applications. The Fibredyne block design provides premium dirt-holding capacity with a low initial pressure drop of 2.5 psi at 4 gpm and a temperature rating of 40 to 180 degrees F. The cartridge is tested and certified by NSF International to NSF/ANSI Standard 42 for material requirements. The CFB-Plus 20BB measures 4.63 inches by 20 inches and fits standard 20-inch Big Blue filter housings. Its high-capacity 4.5-inch-diameter format is rated for more than 50,000 gallons of chlorine taste and odor reduction at 4 gpm. Replace the cartridge every 12 months or when you notice a drop in flow rate. After installation, flush the cartridge before use to clear any carbon fines.