Material: Carbon steel, durable and resistant to deformation under heavy loads. Package includes: 30 pieces of 608zz bearings. (8 mm x 22 mm x 7 mm). Protective covers on both sides retain lubricant and remove contaminants. Ball bearing performance characteristics: low noise. High speed. High temperature resistance. High load capacity. Suitable for skateboards, inline skates, scooters, and other skating applications. Specifications: Outer diameter: 22 mm Inner diameter: 8 mm Thickness: 7 mm