Pentair OMNIFilter RS18-20 Sediment Water Filter, 20-Inch, Whole House Heavy Duty Spun Polypropylene Replacement Cartridge, 20" x 4.5", 50 Micron, keeps your water clean and protect your appliances by removing dirt, sediment and rust particles. It is designed to work best with OMNIFilter BF55 Heavy Duty Filter Housing; Fits All 20" heavy duty housings and can replace any 20" x 4.5" sediment filter cartridge. Gradient density design traps sediment within the cartridge not just on the outer layer for better flow rates and reduced pressure drop. It is manufactured with 100% pure polypropylene and is suitable for use on municipal or well water supplies. It has 60,000 gallon capacity. Replace every 6 months or when you notice a drop in water pressure or water quality