Pentair Pentek NCP-20BB Big Blue Carbon Water Filter, 20-Inch, Whole House Non-Cellulose Carbon Impregnated Pleated Filter Cartridge, 20" x 4.5", 10 Micron. Provides superior sediment filtration and chlorine taste and odor reduction. It fits ALL 20" Big Blue Housing and can replace any 20" x 4.5" carbon filter . Suitable for Municipal and Non Chlorinated Water applications unlike cellulose cartridges. High dirt loading capacity with Minimal pressure drop due to the pleated design. Combination of Pleated Polyester media and carbon filtration produces extended service life.