Culligan CW5-BBS Whole House Premium Water Filter Cartridge, 16,000 Gallons, 3 PackPolypropylene wound cartridge. Advanced level 4 filtering. Reduces the formation of deposits, rust, scale, mud, coarse sand, sand, fine sand, ultrafine sand and silt. Filter life up to 4 months or 16,000 gallons. 5 micron rating. Sold as 3 Pack, The CW5 BBS polypropylene wound heavy duty filtration cartridge works in Culligan model HD 950A whole house filtration systems. Perfect for residential homes, helps protect appliances and pluming from sediment