PMP (Polymethylpentene) is an isotactically arranged aliphatic polyolefin typically sold under the brand name TPX. PMP is a hard, solid material, which can be machined or formed into various optical components like lenses and windows. Despite its high cost, this material has found a home in many applications because of its high melting point and good temperature stability. It is also often used in electrical components e.g. LED molds because it is an excellent electrical insulator. PMP can be used for autoclavable medical and laboratory equipment, microwave components, and cookware. Applications include sonar covers, speaker cones, ultrasonic transducer heads, and lightweight structural parts. It is also FDA compliant for use in food processing machinery. Polymethylpentene is often used in films and coatings for gas permeable packaging.