6307 Ball Bearing, ABEC-5 Japan Quality Deep Groove Csk Bearing

Grade 10 Chromium Steel Balls: High precision balls are within 10/1,000,000″ round, twice as round as the industry standard, at it's highest level

The ABEC scale is an industry accepted standard for the tolerances of a ball bearing. ... Due to these factors, an ABEC 7 classified bearing could perform better than an ABEC 3 bearing. Bearings not conforming to at least ABEC 1 cannot be 

One (1) set of eight (8) Lucky Bearings 8mm ABEC 3 Skateboard Bearings from Lucky Bearings; Rating: ABEC 3; Industry Standard Size: 608 with an 8mm core, 

The ABEC rating system includes grades 1,3,5,7, and 9. The higher the ABEC rating, the tighter the tolerances are, making the bearing a more precision part. High precision and small tolerances are required for bearings to function at very high RPM, in products like high speed routers that must spin at 20 to 30,000 RPM

Jul 13, 2002 - “An ABEC 1 or 3 is all you really need on a skateboard. In skateboarding, you're not using the precision of the bearing.” Heplar thinks the 

It was developed by the Annular Bearing Engineering Committee (ABEC) of ... There are five classes, going from widest tolerances to tightest: 1, 3, 5, 7, and 9

Aug 24, 2015 - The Annular Bearing Engineering Committee (ABEC) created a rating system that has become the industry standard for ball and roller bearing tolerances. ABEC includes five tolerances classes: 1, 3, 5, 7, and 9 with 1 being the widest and 9 the tightest