Bearings make your inline or roller skate wheels freely spin!
Most skate bearings have an ABEC rating from 1-9. The higher the number does not necessarily mean it is better; a higher rating signifies better precision, efficiency, and the possibility of greater speed capabilities, but do not necessarily allow the components to spin faster. The ABEC rating does not specify many critical factors, such as load handling capabilities, ball precision, materials, hardness, degree of ball and raceway polishing, noise, vibration, and lubricant. Due to these factors, an ABEC 3 classified bearing could perform better than an ABEC 7 bearing. In general, a lower ABEC rating works for the vast majority of uses, including most roller and inline skating applications. Higher ratings will help for more specific use cases, such as competitive speed skating, artistic skating, or any discipline that requires a more precise bearing.
Swiss bearings are made with higher-tensile steel or another strong and lightweight material like titanium, meaning a smoother, more durable, longer-lasting roll than traditional steel bearings.
While regular bearings are made from stainless steel, ceramic bearings are made from ceramic silicon nitride (Si2N4). Because ceramic bearings are rounder with a smoother surface and more uniform size, friction is reduced and that can contribute to a less energy required to spin the wheels. A ceramic bearing is also harder than steel bearings (up to 30%), which improves durability, and they also don’t rust so less maintenance should be required.
Tldr: if you are planning to just skate at home, in a parking lot, on the street, or on a court for funsies, then ABEC 1-7 bearings would be fine. If you are training for a competitive roller derby season, skate park contest, or speed skating race, then ABEC 9 or Swiss bearings might get you to go faster. If you are competing in the Blading Cup or Roller Derby World Championships, going for Gold with the USA Inline Speed Skating Team, or just want the absolutely smoothest and fastest roll, then ceramic bearings might help you get an edge over the competition.