Features: This Square Hole Auger Drill Bit set is great for drilling square holes in wood. Reduce labor intensity of construction workers, speed up the construction speed, reduce construction costs for construction, installation, renovation, decoration industries. Fits mortising attachments with 3/4 collars. The whole drill is heat treated,offering higher hardness. Using different specifications of the square hole drill, matching the appropriate power of the square hole machine, you can play a square hole to meet the requirements. Specifications: Type: Square Hole Saw Mortising Chisel Material: high-speed steel Color: Silver Hardness: 56HRC Clamping shank diameter: 19mm (Round) Square hole size: approx. 6.4mm(1/4) 8mm(5/16) 9.5mm(3/8) 12.7mm(1/2) Application: Mainly used for carpentry, applicable to the construction, installation, decoration, decoration industry use. Quantity: 4pcs Package Included: 4x Square Hole Drill Bits Note: 1. The real color of the item may be slightly different from the pictures shown on website caused by many factors such as brightness of your monitor and light brightness. 2. Please allow slight manual measurement deviation for the data.