Bearings come in a range of different options. From ABEC 1-9, skate rated, Swiss and Ceramic. Abec ratings stand for the precision of the bearing. The higher the ABEC reflects how fast the bearing spins. Skate rated is a term made for Bones reds bearings which ensures the bearings and lubricant are engineered specifically for skating. Swiss uses swiss precision for the highest quality available. Bearings made of ceramic are much better quality than most alternatives due to being harder, longer lasting corrosion-resistant, and can work with lighter lubricant for added speed.
Please note – you will need 2 bearings per wheel on skates, skateboard, and scooters.