The ABEC is known to be a rating system. If you are a skater or you are familiar with using the skateboard, then you know that these are two different things. ABEC means Annular Bearings Engineerings Committee. The higher the ABEC values, the higher the bearing of the skateboard overall. The ABEC will mean that you can get the strictest tolerance and will make sure that everything will be correctly made.
ABEC 5 bearings are usually chosen to upgrade the stock bearings of the skateboard. ABEC 7 is known to be more high-class and will sometimes be used by professionals. ABEC 5 is known to be cheaper than ABEC 7.