CONSTRUCTION: The high performance of ULTRASPUN is obtained by a closely controlled manufacturing process using very fine diameter fibers, which build up producing spun bonded layers that give the filter its depth. The outer (upstream) layers contain different graded pore sizes, which act as prefiltration section. The inner (downstream) layers are constructed of fine fibers with the constant pore diameters provide absolute filtration. All ULTRASPUN elements have molded cores, which give them added strength and permit the use of fine fibers. ULTRASPUN cartridge filters are available in polypropylene (USP Series) and nylon (USN Series) with all standard adapters, which are welded directly to the core. No surfactant, binder resin or antistatic agent is used. The fibers are bonded by intertwining during the manufacturing process. ULTRASPUN filters have wide temperature and chemical compatibility due to the choice of materials.