Speed and cleanliness have always been two major issues in the manufacturing process the moc 9 airrr addresses both issues manufactured with the highest quality usa made balls finer polished raceways and a seal system that is different from all other methods of bearing seals in the bearing industry at the present timethe moc 9 buna non contact seal is set into a u channel design in the outer race and a stop on the inner race to keep all foreign particles out of the ball area it also stop