Made from pleated cellulose, the 12-pack of S1 Pentek whole house water filter cartridges is an affordably priced way to keep virtually all sediment and dirt particles 20 micron or larger out of your water. A genuine OE part, these filters are constructed by Pentek with a pleated design helping capture more dirt throughout their lifespan. These filters are recommended for use with chlorinated water only. Order the replacement S1 Pentek whole house water filter cartridge you need today!