General description Professional design ideal for drilling square holes in wood with a mortiser. The square hole drill bit is mainly used in the woodworking field, perfect for construction, renovation, and decoration industries. This set reduces the labor intensity of construction workers while speeding up work and reducing costs. Technical specifications Material: High speed steel Heat treatment hardness: HRC48~50 Sizes: 1/4" (6.35mm), 5/16" (7.94mm), 3/8" (9.5mm), 1/2" (12.7mm) Compatibility and accessories Fits all machines and drill attachments Package includes: 1 piece of each size (1/4", 5/16", 3/8", 1/2") Installation The punch square needs to use a drill, hammer, or other tools (none of these are included)