Professional design ideal for drilling square holes in wood with a mortiser. Fits all machines and drill attachments. Square hole drill bit is mainly used in 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). Why choose this item: Reduces the labor intensity of construction workers while accelerating the speed of work and reducing costs. Perfect for the construction, renovation and decoration sectors. Scope of delivery: 1 piece 1/4'; (6.35mm), 1 piece 5/16" (7.94mm), 1 piece 3/8' (9.5mm), 1 piece 1/2' (12.7mm), Note: The punch square needs to use a drill, hammer or other tools. (None of these items are included). LRFR is committed to providing each customer with the highest possible standard of customer service.