O-shaped ring (also named as O–Ring, O-loop, or O-shaped circle) is a kind of round mechanical gasket. It’s a round elastomer, whose fracture surface is round. Usually, it’s fixed in a groove. During installation, it will be pressed by 2 or more components, thus producing a sealed port. Since it’s cheap in price, easy to manufacture, reliable in function and requires simple installation, O-Ring is the most commonly used mechanical sealing design. O-Ring can be used in static plane sealing, and in dynamic application that have relative movement between parts, such as the axle of rotator pump and piston of hydraulic cylinder.