Designed for professional use in drilling square holes in wood with a mortising machine or mortising attachment. Fits all standard mortising machines and drill press attachments. Ideal for woodworking applications. Made of high-speed steel with heat treatment (HRC4850) for high hardness and durability. Features a lengthened core and high concentricity for improved performance. Available in four sizes: 1/4" (6.35mm), 5/16" (7.94mm), 3/8" (9.5mm), and 1/2" (12.7mm). Helps reduce labor intensity, increase work efficiency, and lower construction time in woodworking, installation, renovation, and decoration projects. Package includes: 1 piece of each size 1/4" (6.35mm), 5/16" (7.94mm), 3/8" (9.5mm), and 1/2" (12.7mm). Note: Square hole drilling requires the use of compatible tools such as an electric drill and hammer. These tools are not included.