Enduro has been producing bearings since before the word "Enduro" became fashionable. Their bearings are an industry-leading design and set the standard for all other bearing manufacturers to match. You may be more familiar with the ABEC standards from the worlds of skateboarding and roller blades, but Enduro has tailored their bearings for the specific demands of cycling. The entry-level industry standard for a bearing is ABEC 1, but Enduro does not produce any bearing which comes in at less than ABEC 3. This means that even if you choose an entry-level Enduro bearing, it is of better quality than another manufacturer's entry-level bearing. These standard ABEC 3/5 bearings are designed for use within bottom brackets or hubs and give outstanding performance and longevity to your components.