608 ZZ Skateboard Bearings, Double Shielded, Silver (Pack of 8) Single-row bearing for supporting radial loads Shields on both sides of the bearing to keep lubricant in and contaminants out Carbon steel for durability and resistance to deformity under heavy loads 34,000 rpm limit with grease lubrication Dimensions suitable for use in such applications as skateboards, inline skates, and scooters