The ABEC rating of a bearing is determined by asking these four questions: 

1.How close is the bore to 8mm in microns (a micron is one millionth of a meter)? 

2.How close is the outer diameter to 22 in microns? 

3.How close is the width to 11mm in microns? 

4.What's the rotating accuracy in microns?

Don't worry if that doesn't mean anything to you - I just wanted to include it in case you're reading this for a paper you might be writing for school!

ABEC isn't the only way to rate skateboard skf bearings, by the way. There is also the International Standards Organization (ISO) system and the [German National Standards Organization (DIN) system. Here is a chart to help you compare: 

ABEC 1 = ISO 0 (or "normal") = DIN P0 

ABEC 3 = ISO Class 6 = DIN P6 

ABEC 5 = ISO Class 5 = DIN P5 

ABEC 11 = ISO Class 4 = DIN P4 

ABEC 9 = ISO Class 2 = DIN P2

It's important to mention that not all skateboard bearings even use the ABEC rating system. Rockets, Ballistech Missiles and nachi Bearings all use their own systems to rate their bearings. This might seem fishy, but it's actually a very good thing. Most bearings used in skateboards were never designed with skateboarding in mind! These companies have developed and built their bearings specifically for skateboards, and they get a lot of respect in the skateboard community because of this.

I hope this explains what ABEC means, and that you now have a better understanding. If you have any questions that weren't covered here, please feel free to write me and ask!Daddies has searched far and wide to find a high quality skateboard bearing for a ridiculously low price! While traveling on the outer edge of the milky way the DBS crew came across these killer double shielded "ABEC 11 bearings" . We quickly mounted these puppies up and took them for a spin. All we can say is cosmic baby!