This specification covers one grade of polytetrafluoroethylene in the form of molded rods, tubes, and shapes. This specification does not apply to rods and tubes over 12 in. (300 mm) in dimension parallel to the direction of applied molding pressure, rods less than 0.750 in. (19 mm) in diameter, and tubes having wall thickness less than 0.500 in. (12.50 mm).