Pentek RFFE20-BB Radial-Flow Iron Reduction Cartridge 4.5"x20"The Pentair Pentek RFFE20 BB Filter Cartridges are designed to provide and easy and effective method of reducing dissolved iron from water, which greatly improves the taste. This iron reduction filter cartridge helps to eliminate the orange and brown stains often found in sinks, toilets, tubs and other plumbing fixtures. It also reduces the possibility of damage to the pipes and water heaters and reduces up to 3 ppm dissolved iron. The iron reduction