Bearing tolerance: including ABEC-1, ABEC-3, ABEC-5, ABEC-7 and ABEC-9.
About ABEC knowledge you should know:
ABEC is developed by the Annular Bearing Engineering Council, a division of the American Bearing Manufacturers’ Association(ABMA).
The ABMA was formerly known as the Anti-Friction Bearing Manufacturers’ Association. Bearings rated under the ABEC systems are typically called “precision bearings”, with a rating or class from ABEC-1 to ABEC-9. ABEC-1 meets a looser tolerance and ABEC-9 meets high precision tight bearing tolerance. We can see real abec grads from official information, which just include ABEC-1, ABEC-3, ABEC-5, ABEC-7, ABEC-9.
So we have to regrettably say that ABEC-8, ABEC-10, ABEC-11, ABEC-13 or even higher grade which you often see in the market are wrong abec grades. These standards are not recognized in the bearing fields, because some companies print these wrong abec grades fro good sales and high profit. There are some explanations about abec on Wikipedia.