Durable Steel MaterialThis square hole drill bit is made of special heat-treated steel, featuring high hardness, extended core and high circularity accuracy. The sharp and continuous blade provides fast cutting and high efficiency. 4 Different Sizes1/4"(6.35mm), 5/16"(7.94mm), 3/8"(9.5mm), 1/2"(12.7mm), 4pcs per set with different slot diameters to meet different drilling requirements. It can be used with a recessed machine and a tenon machine to achieve double effect. High-quality designThe woodworking drill bit features efficient groove geometry, the head with its sharp tooth structure allows easy drilling into wood, and the serrated teeth ensure excellent chip evacuation, thereby reducing the labor intensity of the builder, speeding up construction time and reducing construction costs. U-shaped design with long chip evacuation groovesThe U-shaped design with long chip evacuation grooves makes it easier to evacuate wood chips and improve drilling efficiency. The design of the drill sleeves places the force of the edge of the drill sleeve in a plane, providing more effective protection to prevent cracking at the beginning of use. Wide ApplicationThis square hole drill bit is suitable for wood, including MDF, particle board, channel wood, pine, basswood, etc. Note: It is not suitable for processing metal, glass, plastic, concrete, plaster, etc. Note: The data are all measured manually, please allow 1-3cm error Due to differences in light and display, there may be some color differences, please refer to the actual item received.