KwiK ABEC-5 bearings are constructed of quality chrome steel races and have been proven to deliver a smooth roll time after time. The 5 is part of the ABEC bearing rating system and determines how much “roll” the bearing has. The higher the number, the longer it will take your wheel to stop spinning after you stop pushing. When looking for a set of bearings be sure to consider the quality of the bearing components. Bearings consist of Races, Balls, Cages, and Shields. The main difference between quality bearings and cheap imitations is the material used for the bearing races. Chrome steel races are far superior to cheaper carbon steel races that tend to slow the bearings considerably when pressure is applied to them.