Wood Chisel 4Pcs Square Hole Drill Bit Set, Steel Hollow Chisels Woodworking Tool Set (1/4 -1/2 - 5/16 - 3/8 inch) Professional design ideal for drilling square holes in wood with a mortiser. Suitable for all drills and accessories. 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 work speed and reducing costs. Perfect for the construction, renovation and decoration industries. Scope of delivery: 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 (12.7 mm),/ Note: The square punch can be used with a drill, hammer or other tools. (None of these features are: 1. Professional woodworking drill bit, suitable for construction, installation, renovation, decoration, etc. 2. 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 3. The dimension is the length of the drilled square hole 4. The cylinder diameter of the clamping part is 19 mm. 5. The center of the drill hole is greater than 210 mm, for longer drill centers. Specifications: Sizes: 1/4 (6.35 mm), 5/16 (7.94 mm), 3/8 (9.5 mm), 1 /2 (12.7 mm). Materials: High Speed Steel. DIY Supplies: Woodworking. Use: Wood Drilling/Drilling. Contents Package contents: 1 x 1/4 or 6.35 mm drill bit. 1 x 5/16 or 7.94 mm drill bit. 1 3/8 or 9.5 mm drill bit. 1 1/2 or 12.7 mm drill bit. Note: Since the measurement