O-ring is a type of rubber sealing ring with a circular cross-section. Due to its O-shaped cross-section, it is called an O-ring rubber sealing ring, also known as an O-ring. It began to appear in the mid-19th century as a sealing element for steam engine cylinders.
Due to its affordable price, simple manufacturing, reliable functionality, and easy installation requirements, O-ring is the most common mechanical design for sealing. O-rings can withstand pressures of tens of megapascals (kilopounds). O-rings can be used in static applications as well as dynamic applications where there is relative motion between components, such as the shaft of a rotary pump and the piston of a hydraulic cylinder.