Abec bearings grades explained

[budfish]

Are *all ABEC precision bearings really manufactured to the correct tolerances ?
We have to believe that they are until it is proven otherwise. If the bearings are labelled as ABEC 7 then in most countries the manufacturers of the bearings are compelled by law to provide ABEC 7 bearings. Some of the low prices offered for high precision bearings in some retailers does look a little strange though. Manufacture of high precision bearings is not cheap, although the costs can be kept lower if other quality controls are not in place. Our quality supplier has recently checked the tolerances of a set of bearings that was purchased and labelled as "ABEC 5". The bearings did indeed meet the standard of ABEC 5, but more costly tests would be needed to check all of the other important quality factors relating to the bearings (and many of these other factors are more relevant to rc racing)

These relate to bearings and not balls!!!