Pentek P1 Spun Polypropylene Filter Cartridge, 9-3/4" x 2-3/8", 1 Micron Reduces sand, silt, scale, and rust particles in residential, commercial, and municipal drinking water Nominal filtration rating of 1 micron Spun polypropylene for resistance to chemicals and bacteria Initial pressure drop of 0.6 psi at a flow rate of 5 gpm Temperature range of 40 to 145 degrees F (4.4 to 62.8 degrees C).