The Faithfull High Speed Steel Rosehead Chubby 90° included angle Countersink is used for countersinking screw holes for flush fitting of screw heads in mild steel, plastics and non-ferrous metals.They are also suitable for working on wood, plywood, MDF, and other man-made boards. They can be used in both hand tools, and power drills. Specifications: Type: Rosehead - Chubby.Size: 13mm (1/2in).Shank Diameter: 6mm (1/4in).Additional Information:• Countersink Type: Countersink• Size (mm): 13