A ring gasket is a part that helps tighten one surface against another, mainly applied on equipment pipes, joints, and flanges. Variants include the materials used, which can be rubber, metal, PTFE, or any combination of these. Ring gaskets are made to face pressure and heat forces as well as resist chemicals. They are very good for areas where fluids or gasses are to be sealed, like ... https://goodrichgasket.com/Ring-Type-Joint-Gasket