608zz Bearings: Single-row bearing for supporting radial and axial loads. Shields on both sides keeping lubricant in and contaminants out. Material: Carbon steel, durability and resistance to deformity under heavy loads. 34,000 RPM limit with grease lubrication. It's suitable for use in skateboards, inline skates, scooters, and other skating applications. Package Included: 10pcs 608zz bearings.