Professional wood drill bit, suitable for construction, installation, renovation, decoration, etc. The workpiece forms a drilled hole by the rotating body, while the impact of using the percussion force is transmitted to the outside of the body, the material creates a round hole and a square head, in one go, and the dust can be discharged through the tube. Professional design ideal for drilling square holes in wood with a mortiser. Fits all machines and drill attachments. The square hole drill bit is mainly used in the woodworking field. Material and size: Made of high-speed steel. Heat treatment, HRC48~50, high hardness, elongated center, high concentricity; 4 sizes: 1/4" (6.35mm), 5/16" (7.94mm), 3/8" (9.5mm), 1/2" (12.7mm). Reduces labor intensity for construction workers while accelerating work speed and reducing costs. Perfect for the construction, renovation, and decoration industries. 1 pc 1/4" (6.35mm), 1 pc 5/16" (7.94mm), 1 pc 3/8" (9.5mm), 1 pc 1/2" (12.7mm)