Description: Description: Feature This Mortising Chisel is great for drilling square holes in wood with a mortising machine or a mortising attachment. Square hole drill can not be used on an electric drill, drill square holes need to fit a square hole drill drilling (mortise and tenon machine) to use. Mortise and tenon square hole drilled by the terrible + outer sleeve in the middle of the combination. Reduce labor intensity of construction workers, speed up the construction speed, reduce construction costs for construction, installation, renovation, decoration industries. Specifications: Size: 1/4 inch (6.35mm), 5/16 inch (7.94mm), 3/8 inch (9.5mm), 1/2 inch (12.7mm) Material: high-speed steel Hardness: HRC 48-50 Color: silver Clamping shank diameter: 19mm (Round) Length: 210mm Package Included: 1X Drill Bit Specifications: Size: 1/4 inch (6.35mm), 5/16 inch (7.94mm), 3/8 inch (9.5mm), 1/2 inch (12.7mm) Material: high-speed steel Hardness: HRC 48-50 Color: silver Clamping shank diameter: 19mm (Round) Length: 210mm Package Included: 1X Drill Bit