Features: Material: The square hole drill is made of high-speed steel. After heat treatment, it has a high-hardness drill, a for sharp square chisel, and a long service life. Size: Provide 4 different sizes for you to choose, 6mm, 6.4mm, 8mm, 9.5mm. These rectangular drill bit sets can meet most of your needs. High working efficiency: woodworking drill bit set, long core and square chisel, easy to for key holes in wood, and then you can quickly get different mortises. In addition, it can also save labor. Available applications: These woodworking mortise chisel bit sets are suitable for drilling square holes in wood with a mortise machine or mortise attachment. In addition, it is suitable for electric drills, hammers and other tools. Reduce the labor intensity of construction workers, speed up construction, and reduce construction costs in construction, installation, decoration, and decoration industries. Specifications: Material:High-Speed Steel Color :Silver Size1: Approx.61x133x19x6.5mm/2.4x5.2x0.74x0.25inch Size2: Approx.134x58x19x8mm/5.27x2.28x0.074x0.31inch Size3: Approx.118x41.5x19x6.4mm/4.64x1.63x0.74x0.25inch Size4: Approx.118x41.5x19x6mm/4.64x1.63x0.74x0.23inch Note: 1.Please allow 1-2mm errors due to manual measurement, make sure that you do not mind before you order. 2.Due to the difference between different monitors, the picture may not reflect the actual color of the item. Package includes: 1xDrill Core