Features: thermoplastic material, high chemical resistance with excellent corrosion resistance and heat resistance, low coefficient of friction, almost unconditional resistance to oxidation. Weather aging and aging, the drawback is not outstanding sealing performance. Description: PTFE retaining ring contains single ring and double ring, single ring opening 22 ° slope, double ring opening  30 ° slope, Standard: MS-27595; the MS-28774; Japanese standards, Chinese standards.