It is made of a rubber ring and a metal ring that are integrally bonded and vulcanized. It is a sealing ring used to seal threads and flange connections. The ring includes a metal ring and a rubber seal. The metal ring is treated with anti-rust treatment, and the rubber ring is generally made of oil-resistant nitrile rubber or fluorine rubber. Combination pads are available in metric and imperial sizes, and the standard JB982-77 stipulates the combination of metal pads and rubber for combination pads. Combination sealing washers are used for sealing threaded pipe joints and screw plugs. They are generally used together with ferrule-type pipe joints to block oil ports. They are mainly used for end-face static sealing of the threaded joints of hydraulic valve pipe joints. They are applicable to British and American standards. End face static sealing at the connection between inch thread and French and German standard metric thread. Combination sealing gaskets can be divided into type A and type B according to their structural forms; they can be divided into full-pack and half-pack according to the different rubber coatings.