General description This 4pcs Woodworking Square Hole Drill Bit Set is designed for carpentry, construction, decoration, and industrial applications. It includes drill bits that create square holes in wood using a mortising machine or attachment, significantly reducing labor intensity and speeding up construction processes. Technical specifications Square Hole Sizes: 1/4 inch (6.4mm), 5/16 inch (8mm), 3/8 inch (9.5mm), 1/2 inch (12.7mm) Drill Bit Material: Metal Clamping Shaft Diameter: 19mm (0.75 inch) Usage Ideal for drilling square holes in wood Compatible with mortising machines and attachments Other information Package includes: 4pcs Square Drill Bits (other accessories not included) Note: Other dimensions are shown in the picture; please avoid 1-2mm error due to manual measurement.