Product Description: Sizes: 1/4" (6.35mm), 5/16" (7.94mm), 3/8" (9.5mm), 1/2" (12.7mm). Materials: High Speed Steel. DIY Supplies: Woodworking. Usage: Wood drilling/drilling. Package content: 1 drill bit of 1/4" or 6.35mm. 1 drill bit of 5/ 16" or 7.94mm. 1 3/8" or 9.5mm drill bit. 1 1/2" or 12.7mm drill bit. < p>Professional design ideal for drilling square holes in wood with a mortiser. Fits all drill machines and 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). 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 should use a drill, hammer or other tools. (None of these are included).