High quality - these square hole drill bits made of high speed steel, through heat treatment, with high hardness drill bits and sharp edge square chisel, long service life Widely Used - Ideal for drilling square holes in wood with a mortising machine or mortising attachment. Easy to Use - It will achieve double effect by using it with mortise and tenon machine. Punching square holes requires electric drill, hammer or other tools. Save time - these woodworking chisel bits can reduce the labor intensity of construction workers, accelerate construction speed, reduce construction costs for construction, installation, renovation,decoration industry Drills precise holes with little pressure - Using different specifications of the square hole drill, corresponding to the appropriate power of the square hole machine, you can play a square hole to meet the requirements - 1/2 inch (12.7 mm), 1/4 inch (6.4 mm), 3/8 inch (9.5 mm), 5/16 inch (7.94 mm)