Description: 45 steel to create, the surface black treatment, more durable, can handle wood, iron-free metal, plastic and rubber. 1/4'' (6mm) shank suitable for most electric & cordless drills. Used for grinding, polishing, shaping & burnishing wood surfaces. Use with handheld electric or pneumatic tool drive (can also be used in machine tool). Uses: Suitable for wood, plastic and other soft materials, carving, carving, chamfering, hollowing, grooving, reaming and so on. Specification: Material: #45 Steel Color: Silver Polished wood head with the largest diameter: 13mm Shank Diameter: Approx. 6mm/ 0.24inch Package Includes: 5 Pieces Steel Rotary Burr Set Note: The color may have different as the difference display, pls understand. Please allow 1-3mm error due to hand test