Formed by the rubber ring and rings and adhesive curing, are used to seal the threaded and flanged sealing ring, ring consists of a metal ring and a rubber seal. Metal ring rust, rubber rings generally use oil resistant nitrile rubber or Viton. Combination mat have both metric and Imperial sizes, JB982-77 provisions of the standard combination pad metal pads plus rubber combinations. Combined sealing gaskets for fittings and screw plug seal, it and generally use bite type fitting, used to block oil, mainly used for hydraulic valve fitting thread connections of static seals, applicable United Kingdom and the United States for unified inch screw threads, and France, and Germany standard metric thread connections of static seals and so on. Combined sealing gaskets according to the structure can be classified as type a, type b; according to the package can be divided into different packages, half a pack of gum.