Polyetherimide (PEI) often is sold by the tradename Ultem® PEI, and is available in a natural amber color and black. This material is an unreinforced amorphous thermoplastic material. It offers an excellent combination of mechanical, thermal and electrical properties. It is suitable for structural components requiring high strength and rigidity at elevated temperatures. Its low flammability and low levels of smoke exhaust during combustion make PEI a very good choice for electrical/electronic insulators.