Made of high-speed steel. Heat treatment, HRC48~50, high hardness, lengthened core, high concentricity. ▲ Great for drilling square holes in wood with a mortising machine or a mortising attachment. Fits all mortising machines and drill press attachments. Square hole drill is mainly used for woodworking aspects. ▲ It will get double effect by matched use with mortise and tenon machine.The square hole punching needs to use electric drill, hammer & other tools. ▲ Reduce labor intensity of construction workers, speed up the construction speed, reduce construction costs for construction, installation, renovation, decoration industries.