Polyethylene is the most widely used polymer in a family of Polyetherimide (PEI) Engineered Plastics. It is characterized as economical, tough, easy to process, light weight with excellent chemical and gamma ray resistance. It has low moisture absorption, good impact strength, a low coefficient of friction, and excellent low temperature and electrical properties. It is available in several grades with a variety of properties. Some are flexible, others are rigid; some have more impact strength, and while some have good clarity, others are opaque.