6Pcs 6.4-16mm HSS Twist Square Hole Drill Bits Auger Mortising Chisel Extended Saw for Woodworking Tools

Material made of high-speed steel, heat treated to HRC48-50. The carbide drill is sharp, resistant to wear, and has high hardness. The U-shaped design makes it easier to remove wood chips and enhances drilling efficiency. Not recommended for drilling metal, glass, plastic, concrete, gypsum board, etc. It is recommended to utilize the square hole drill with the mortise and tenon machine. These bits are not compatible with manual drills. In case you wish to use these bits on a drill press, additional attachments for the drill press are required. Six square hole drill bits available in sizes of 1/4inch (6.4mm), 5/16inch (8mm), 3/8inch (9.5mm), 0.394in (10mm), 1/2inch (12.7mm), and 5/8inch (16mm).