Features: Deep groove ball bearings. These bearings are pre-lubricated with grease. Smooth operation, low friction, high performance, and long life. Applications: skateboards, roller blades, inline skating, scooters. Specifications: Model: 608ZZ Material: Chrome Steel Color: Gray Size: 8mm x 22mm x 7mm Inner Diameter: 8mm Outer Diameter: 22mm Thickness: 7mm Suitable For: 3D printers Quantity: 1 Set (10 Pieces) (other accessories shown in the picture are not included) Note: 1. Transition: 1cm = 10mm = 0.39inch 2. Please allow 01cm error due to manual measurement. Please ensure you are comfortable with this before purchasing. 3. Due to differences between monitor displays, the picture may not reflect the actual color of the item. Package Includes: 10 x 608ZZ Bearings (no retail packaging)