Steyr O Ring 18 X 1.5An O-ring is a doughnut shaped seal typically used to prevent the passing of air or fluid. In other words, O-rings are used to keep fluid or air IN or OUT of a defined space. Typically made of rubber and used especially in swiveling joints. They prevent leaks in everything from pumps and valves to cylinders and connectors and prevents the gas leakage.Contact us at 70822-33324, if the product is in pre-order status.