O-Ring 20.35 x 1.78 for fwb 800 Model

"An O-ring is a doughnut, or torus 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. "