# What does ABEC mean? also what's the difference between YYJ speed and spec?

**URL:** https://forums.yoyoexpert.com/t/what-does-abec-mean-also-whats-the-difference-between-yyj-speed-and-spec/14485
**Category:** General Yo-Yo
**Created:** [May 16, 2010, 10:15pm UTC](https://forums.yoyoexpert.com/t/what-does-abec-mean-also-whats-the-difference-between-yyj-speed-and-spec/14485 "2010-05-16T22:15:19Z")
**Posts on this page:** 1
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### Author: ![Yummy](https://sea1.discourse-cdn.com/flex015/user_avatar/forums.yoyoexpert.com/yummy/32/14065_2.png) [@Yummy](https://forums.yoyoexpert.com/u/Yummy)
#### Post date: [May 17, 2010, 12:22am UTC](https://forums.yoyoexpert.com/t/what-does-abec-mean-also-whats-the-difference-between-yyj-speed-and-spec/14485/6 "2010-05-17T00:22:45Z")

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To paraphrase the link icthus gave, the ABEC rating has to do with tolerances. How close to spec the inside and outside diameter are. That really isn’t important with yo-yos. The rotating accuracy of bearings is extremely important in a precision tool such as a lathe but doesn’t matter on a yo-yo.

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