O-Ring is a kind of rubber sealing ring with a circular cross-section to seal various fluids such as air, water, and oil. Because its cross-section is o-shaped, it is called o shape rubber seal, also called o-Ring. It is the most widely used element in hydraulic and pneumatic transmission systems. It is mainly used for mechanical parts to prevent the leakage of liquid and gaseous media under static conditions. In some cases, o-rings can also be used as axial dynamic sealing of reciprocating motion and low-speed rotating motion.

For different types of fixed sealing or dynamic sealing applications, o-ring seals provide designers with an effective and economical sealing element. As a two-way sealing element, the o-ring is installed in the medium groove, and the initial compression in the radial or axial direction during installation gives the o-ring its own initial sealing ability. The sealing force produced by the system pressure and the initial sealing force is combined into the total sealing force, which increases with the increase of the system pressure.