ABEC scale
（重定向自ABEC）
The ABEC scale is an industry accepted standard for the tolerances of a ball bearing. It was developed by the Annular Bearing Engineering Committee (ABEC) of the American Bearing Manufacturers Association (ABMA). There are five classes from largest to smallest tolerances: 1, 3, 5, 7, and 9. There is no ABEC 11 standard despite the claims of some sellers. The higher ABEC classes provide better precision, efficiency, and greater speed capabilities, but do not necessarily allow the components to spin faster. The ABEC rating does not specify many other critical factors, such as smoothness of the rolling contact surfaces, ball precision or quality/type of steel used.