Pentek CW-MF String-Wound Polypropylene Filter Cartridge, 9-7/8" x 2-1/4", 30 Micron Reduces sand, silt, scale, and rust particles in residential and municipal drinking water and industrial fluid applications Nominal filtration rating of 30 microns Polypropylene cord wound on a polypropylene core for strength and high dirt-loading capacity Initial pressure drop of less than 1 psi at a flow rate of 10 gpm Temperature range of 40 to 165 degrees F (4.4 to 73.9 degrees C).