Seal standard, O-ring standard, the standard rubber seal, ring the national standard: according to seal the O-ring cross section can be divided into standard, star-ring standard, X-ring standard, hollow tube ring standard, V-ring standard, L-ring standard, U-ring standard, Y-ring standard, shaped seal standard. Press material can be divided into nitrile rubber seals, rubber seals, neoprene seals, EPDM seals, hydrogenated nitrile rubber seals, silicone ring, Viton seals, silicon fluorine rubber seal circle. Ring standard =ID * CS.