Oust Bearings: MOC 9 Air (set of 8) Unique bearing design provides tighter tolerances beyond the ABEC scale. Out performs the best ABEC 9, Swiss, and ceramic bearings. Manufactured with the highest quality USA made balls with high Rockwell hardness, and finer polished raceways. 2 Buna Seals that keep all foreign particles out of the ball area better than any other seals available. Made in USA