The 6-PACK Pentek R30-20BB (155430-43) is a 30-micron pleated polyester filter cartridge. That is used for reducing sediment in water. Good for general sediment reduction and well suited for non-chlorinated water supplies. In some applications the R30-20BB can be removed and cleaned to extend cartridge lifespan. 20″ X 4.5″ BB. Filter Media :Pleated polyester. Filter Life: 6 months. Application : City or well water. Reduction: Sediment sand, dirt, silt, rust, and scale particles.