Abec vs. Skate Rated™ - Support - Bones BearingsIn an application like this, an ABEC - 7 or 9 bearing rating may be appropriate. However, a skateboard with 54mm wheels turning 20,000 RPM will be traveling The ABEC Myth | TransWorld SKATEboardingJul 13, 2002 - The ABEC rating system uses odd numbers, ranging from 1 to 9. The higher the number, the tighter the tolerance of the bearing, and thus, the 
Abec 9 Skateboard Bearings | Lily BearingAbec-9 has been the highest grade in bearing industry. The Abec 9 rollerblade bearing can be applied to any harsh conditions with high speed requirementsBullseye Bearings ABEC 9 Skateboard  The Bullseye ABEC 9 Bearing. Bearings are circular pieces of steel with flat sides that contain eight lubricated balls, their purpose is to keep wheels running ABEC scale - WikipediaThe ABEC scale is an industry accepted standard for the tolerances of a ball bearing.  There are five classes from largest to smallest tolerances: 1, 3, 5, 7, 9