Pentair Pentek RFFE20-BB Big Blue Water Filter, 20-Inch, Whole House Radial Flow Iron Reduction Replacement Cartridge, 20" x 4.5", WhitePentair Pentek RFFE20-BB Big Blue Water Filter, 20-Inch, Whole House Radial Flow Iron Reduction Replacement Cartridge, 20" x 4.5", White, greatly improves taste by filtering up to 3 PPM of dissolved iron and eliminates metallic taste. It prevents rust stains on sinks, toilets, and plumbing fixtures and prevents appliance damage. It provides whole house filtering on main water line and works great for well water. It fits all 20" Big Blue Housing and can replace any 4.5" x 20" Iron reducing filter. It can be replaced every 3 months for 3PPM reduction with a family of four.Pentair Pentek DGD-5005-20 Big Blue Sediment Water Filter, 20-Inch, Whole House Heavy Duty Dual-Gradient Density Spun Polypropylene Replacement Filter Cartridge, 20 inch x 4.5 inch, 5 Micron, WhitePentair Pentek DGD Series Cartridges are manufactured from 100% pure polypropylene and are sized for use in Pentair Pentek Big Blue Filter Housings (and other heavy duty filter housings). DGD Series Cartridges are designed for purity and will not impart taste, odor or color to the liquid being filtered. Additionally, the polypropylene construction provides superior chemical resistance and is not prone to bacterial attack. The DGD Series' advanced design combines selective final filtration with appropriate pre-filtration to achieve up to three times the dirt holding capacity of similar size sediment cartridges and even greater capacity than standard spun or string-wound cartridges. The larger diameter of the filter reduces the particle load, allowing it to operate at higher velocities. The effective filter depth is increased to a full 233%. This increased depth provides very high particulate reduction efficiencies and added loading capacity. The design and performance characteristics of the DGD Series Cartridges make them an excellent choice for all residential, rural, municipal and commercial applications.