3/16" Thick, Round Cross Section, Shore 55, -300 to 500°F PTFE is a thermoplastic fluoroethylene resin that offers excellent chemical and temperature resistance. It also offer low friction, dielectric strength, zero water absorption, toughness and flexibility.|Round cross-section shapes can be used in both static and dynamic applications. They are used as a mechanical seal or gasket and are seated in a groove and compressed during assembly between two or more parts.