SincereetaliThis is a countersink drill bit set which is 2 in 1 hole drilling and countersinking, very professional and helpful in woodworking. Features: Including a mini hex wrench. Detachable and the length is adjustable. Apply to the drilling machine which has clamp or joint. These countersink drill bits work great in wood chipping and woodworking. It includes 4 sizes in a countersink drill bit set (6#, 10#, 13#, 16#). High speed steel drill and carbon steel countersink and countersink machine. Specifications: Material: High speed steel + carbon steel Hex Shank Diameter: 6.35mm Package Weight: Approx. 86g/3.05oz Package Size: Approx. 11 * 6.5 * 1.5cm / 4.33 * 2.56 * 0.59in Package List: 4 * Countersink Drill Bits 1 * Hex Key