Material, carbon steel, durability and resistance to deformation under heavy load.Package includes: 30pcs 608zz bearings. (8mm x 22mm x 7mm)Protective covers on both sides retain lubricant and remove contaminants.Performance characteristics of ball bearings, low noise. High speed. High temperature resistance. Resistance to high loads.Suitable for skateboards, inline skates, scooters and other skating applications.Specification:External diameter: 22 mmInternal diameter: 8 mmThickness: 7 mmAbout Shipping: All items will be shipped within 3 business days after the payment is received. Most times you will receive them within 8-12 days then. The specific delivery time is depend on circumstances.Any questions, please feel free to contact usDuring the shopping process, if you have any questions, please feel free to consult us, we will reply you within 24 hours, wish you a happy shoppingThanks for your cooperation and we'll make you feel satisfied.