General description 4 Pcs Square Hole Drill Bit Set is designed for creating square holes in wood using a mortising machine or mortiser. This set includes four different sizes to accommodate various drilling needs. Technical specifications Material: High Speed Steel Hardness: HRC48-50 Sizes: 1/4" (6.35mm), 5/16" (7.94mm), 3/8" (9.5mm), 1/2" (12.7mm) Installation Used in conjunction with a mortising machine for optimal results. If drilling manually, tools such as a hand drill and a hammer are required. Usage Ideal for drilling square holes in wood. Standard chip design allows for easy removal of wood chips, improving drilling efficiency. Reduces labor intensity and accelerates construction speed, lowering costs in construction, installation, renovation, and decoration industries.