Ultem® PEI is a semi-transparent high-temperature plastic. It is used to make custom parts as well as fasteners such as screws, hex nuts, washers, threaded studs, and spacers. It can be both molded and machined. Ultem® PEI fasteners and custom hardware are also available in glass filled grades for greater strength and stiffness. (Glass-filled grades are opaque.) Ultem® 1000 is the natural grade, and Ultem® 2300 is the glass filled grade. Ultem®