The Pentek CBC-20BB is a nominal 0.5 micron Pentek CBC20-BB Carbon Block Water Filter Cartridge. The Pentek CBC-20BB water filters produce healthier, better-tasting drinking water. The Pentek CBC-20BB reduces 99.5% of Cryptosporidium, Giardia, Entamoeba,and Toxoplasmacysts (based on manufacturer's internal testing). The CBC-20BB water filters have enhanced dirt holding capacity. The Ametek CBC-20BB water filter cartridges are an ideal choice for a wide range of residential, food service, commercial and industrial applications. They also make excellent polishing filters or pre-filters in applications requiring fine filtration and high capacity.