Professional design, ideal for drilling square holes in wood with a mortiser. Fits all machines and drill bits. Square hole drills are mainly used in woodworking. Material and size: Made of high speed steel. Heat treatment, HRC48~50, high hardness, extended center, high concentricitysizes: 1/4 inch (6.35 mm), 5/16 inch (7.94 mm), 3/8 inch (9.5 mm), 1/2 inch (12.7 mm). Why choose this item: Reduces the labor intensity of construction workers, at the same time accelerates the working speed and reduces costs. Perfect for construction, renovation and decoration field. Package includes: 1 piece 1/4" (6.35 mm), 1 piece 5/16" (7.94 mm), 1 piece 3/8" ( 9.5 mm), 1 piece 1/2 inch (12.7 mm), Note: The punch square must be made with a drill, hammer or other tools. (None of these items are included).