HSS Woodworking Twist Drill Bit Set Mortise Bit Set Square Drill Bit Mortise Chisel Square Hole Woodworking Drill Bit Set Description: Made of High Speed Steel This type of square hole drill bit can be used for a long time as it is not easy to break or damage. Square hole drill bits are wear-resistant and can be used for a long time. It is not easy to get damaged. The square bit is suitable for different positions, meeting your needs and making woodworking more convenient and easier. The square bit is not easy to get damaged. damage. It may be damaged if used directly with the electric drill, need to contact it in the mortise, extend the working time of the drill. There are different sizes to choose from, you can order according to your needs. Specification: Material: High speed steel. < p>Color: As pictures show. < p>Size: 6.4mm, 8mm, 9.5mm, 12.7mm Package includes: 1 x square drill.