[Square Hole Size]: 1/4 inch / 6.4mm, 5/16 inch / 8mm, 3/8 inch / 9.5mm, 1/2 inch / 12.7mm. Refers to the edge length of the square hole drilled by the square bit. [Application]: This mortising chisel is ideal for drilling square holes in wood with a mortising machine or mortising attachment. mortise. Suitable for use in the wood, construction, installation and decoration industries. [Features]: Reduce the labor intensity of construction workers, speed up the speed of construction. [Material]: high strength and hardness, made of high quality material, wear resistance and easy to use. [Note]: other dimensions are shown in the picture. Please avoid 1-2mm errors due to manual measurement. Product Description Item Descriptions: -[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 edge length of the square hole drilled by the square bit. -[Application]: This mortising chisel is ideal for drilling square holes in wood with a mortising machine or an accessory to mortise. Suitable for use in the wood, construction, installation and decoration industries. -[Features]: Reduce the labor intensity of construction workers, speed up the speed of construction. -[Material]: high strength and hardness, made of high quality material, wear resistance and easy to use. -[Note]: d other dimensions are shown in the picture. Please avoid 1-2mm errors due to manual measurement. Package: 4pcs Square Drill Bit (Note: other accessories are not not included.) Item Specifications: Drill Bit Material:Metal Clamp Shank Diameter:19mm/0.75inch