Features: 1) Materials: zirconia 2) Usage: for bearings, inspection, and other rolling conditions 3) Exported to Japan, Korea, North America and Europe 4) Diameter: 1/64" ~ 5/4" 5) Precision: G10 ~ G20 Specifications: 1) With density of 6.05g/cm3 2) Fine crystalline 3) Never rust, and can roll without oil or grease