This filter cartridge is made of textile fiber (polypropylene string, Absorbent cotton string, acrylic fiber yarn, fiberglass). According to the specified precess, it is winded tightly with the string in the polyporous core, structured by loose outer layers and tight inner layers, the filter cartridge porous outside it is big, inside it is small, it has the true deep filtration effect, it can remove the suspension, rust, particles, etc.