National Oil Seals are designed to prevent leakage around valves, shafts, and other moving parts of the vehicle. These seals prevent fluid from leaking out between the shaft and the housing. They have a flexible lip that rubs against the shaft to prevent the leakage or ingress of fluids and dirt. These seals prevent abrasives, corrosive moisture and other harmful contaminants from entering the machines. These industrial seals are available in small-bore sizes zero to 13 inches, as well as in metric and high-temperature varieties.