Features: 1.Made of high quality alloy steel. Heat Treatment, High Hardness, Lengthened Core, High Concentricity. 2.Great for drilling square holes in wood. 3.Mainly used for woodworking aspects. 4.The professional wood drill bit, suitable for renovation, construction, installation, decoration industry, etc. 5.Reduce the labor intensity of workers. 6.Reduce construction costs for installation, renovation, decoration industries. 7.Fits all mortising machines and drill press attachments. 8.Come with 4pcs, meet your different needs. Notice: Please allow 1-3cm deviation due to manual measurement Actual color may be slightly different from the image due to different monitor and light effect Description: Material: Alloy Steel Size: 1/4"(6.35mm), 5/16"(7.94mm), 3/8"(9.5mm), 1/2"(12.7mm) includes: 1 set x Woodworking Drill Tools