ABEC classes as set by the Annular Bearing Engineers Committee of the American Bearing Manufacturer’s Association (ABMA). These standards are also accepted by (ANSI) American National Standards Institute and by international agreement for the standards developed by (ISO) International Organization of Standardization.
The ABEC scale is a system of rating the manufacturing tolerance of precision bearings. The system was developed by the Annular Bearing Engineering Council (ABEC), 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 1 to 9. ABEC 1 meets a looser tolerance and ABEC 9 meets high precision tight bearing tolerances.
The special statement is that inline skates bearing abec only include abec1, abec3, abec5,abec7 and abec9. We often see some online merchants promoting higher abec bearing 608z, including abec13, abec15 and abec17… These standards are not recognized in bearing field, just merchants’ promoting slogan. There are some explanations about abec on Wikipedia.