Abec relates to the precision of how the bearings are made... some people say that the higher the rating the faster you can skate, although that is not proven. Check this site for a little more info... http://web.skatefaq.com:81/bearings.html Ps. I don't skate myself, but my partner has been skating for about 15 years.

just the speed they produce in the wheels.

its the speed. i dont know what makes them faster.

What Are ABEC Bearings? The ABEC scale is a system for rating the manufacturing tolerances of precision bearings. The system was developed by the Annular Bearing Engineering Committee or Council (ABEC) of the American Bearing Manufacturers Association (ABMA). The American Bearing Manufacturers Association was formerly known as the Anti-Friction Bearing Manufacturers Association. What Does ABEC Mean? The ABEC scale is a system for rating the manufacturing tolerances of precision bearings. The system was developed by the Annular Bearing Engineering Committee or Council (ABEC) of the American Bearing Manufacturers Association (ABMA). The American Bearing Manufacturers Association was formerly known as the Anti-Friction Bearing Manufacturers Association. Bearings rated under the ABEC system are typically called "precision bearings", and they are rated with a number from 1 to 9, with the higher number assigned to bearings manufactured against a higher standard of precision (high number = tighter tolerances = more expensive bearing). What Does Tolerance Mean? Tolerance is the amount of variation from an absolute exact measurement that is permitted during the manufacturing process.