Bearings are circular pieces of steel with flat sides that contain eight lubricated balls, their purpose is to keep wheels running smoothly. The steel balls help disperse weight and ease tension between the wheels and axle. The ABEC scale is an industry accepted standard for the tolerances of a ball bearing. The Bullseye ABEC 9 bearing is best for very fast speeds and high precision. For example, if you wanted to achieve high speeds in a downhill style skate, these bearings will do the job.