An "O-링" (O-ring) is a circular sealing device made from flexible materials like rubber or silicone. It is designed to fit into a groove and create a tight seal between two surfaces, preventing the leakage of fluids or gases. O-rings are commonly used in various applications, including automotive, aerospace, and plumbing systems. These seals are available in different sizes and materials to suit specific needs. The effectiveness of an O-ring depends on factors such as temperature, pressure, and the type of fluid it is sealing. Proper installation and maintenance are essential for optimal performance and longevity.