4-Piece Square Hole Drill Bit Set for Woodworking, 6.4mm / 8mm / 9.5mm / 12.7mm Wood Mortising Chisel Set for Carpentry, Construction, Decoration, and Industry

[Square Hole Size]: 1/4 inch / 6.4 mm, 5/16 inch / 8 mm, 3/8 inch / 9.5 mm, 1/2 inch / 12.7 mm. Refers to the length of the edge of the square hole drilled by the square drill bit.[Application]: This mortising chisel is ideal for drilling square holes in wood with a mortising machine or mortising attachment. Suitable for use in the woodworking, construction, installation, and decoration industries.[Features]: Reduces the workload of construction workers and speeds up construction.[Material]: High strength and hardness, made of high-quality material, wear-resistant and easy to use.[Note]: Other dimensions are shown in the image. Please allow for errors of 1 to 2 mm due to manual measurement.