This is a set of countersink drill bit that is bore hole and chamfer 2 in 1, very professional and helpful in woodworking. Features: Including a mini hex wrench. Detachable and the length is adjustable. Apply to the drilling machine that has collet or joint. These countersink drill bits works great in wood and wood chip. It includes 4 sizes in one countersink drill bit set(6#, 10#, 13#, 16#). High speed steel drill and carbon steel countersink and chamfering 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