The Rush Bearings Downhill Speed Bombers Ceramic Bearings Skateboard Bearings are made to lash your wheels to the axle. Make it easy on yourself by starting with high-quality Rush Bearings Downhill Speed Bombers Ceramic Bearings Skateboard Bearings.Note: All skateboard bearings are the same size. These bearings will fit any skateboard.Sold in sets of 8 bearings to complete four skateboard wheels for one skateboard, two bearings mount each skateboard wheel to its truck axle. The industry standard size is 608 with an 8 mm bore, a 22 mm outer diameter and a width of 7mm. Bearings rated under the ABEC scale are typically called precision bearings which are rated by a number from 1 to 9. Higher ratings are assigned to bearings manufactured against a higher standard of precision.