The Pentair OMNIFilter RS1 is a pleated cellulose sediment replacement cartridge that reduces dirt, sand, silt, rust, and other particulates down to 20 microns. Designed for standard 10" x 2.5" whole house filter housings, the RS1 helps protect your plumbing, water heater, and household appliances from sediment-related damage. The pleated cellulose media is wrapped around a rigid polypropylene core, providing a larger filtration surface area than non-pleated designs. This increased surface area delivers greater dirt-holding capacity and more consistent water flow over the life of the cartridge. With a 15,000-gallon capacity, each cartridge provides approximately 3 months of filtration. The RS1 pairs best with Pentair OMNIFilter U24, U25, U30, OB1, and WH5 whole house systems, and fits standard 10" x 2.5" housings from other major manufacturers. This cartridge is designed for use with chlorinated (city) water supplies. The 2-pack ensures you have a replacement ready when it is time to change your filter.