Features: 1. Complete Set: This package includes 1 square hole drill bit adapter and 4 enduring carbide square hole drill bits in sizes 1/4 inch (6.4 mm), 5/16 inch (8 mm), 3/8 inch (9.5 mm), and 1/2 inch (12.7 mm), making it ideal for a range of woodworking tasks. 2. High-Quality Materials: The drill bits and adapter are crafted from resilient carbide material, ensuring significant durability, rapid cutting speeds, and lasting sharpness. These high-quality tools will securely hold your wood during drilling. 3. Versatile: These drill bits are suitable for both bench and hand drills, making them extremely versatile. They are ideal for woodworking, furniture production, and various other related industries. 4. Easy to Operate: With a precision design, these drill press mortise attachments and drill bits are easy to use and work more conveniently and faster than traditional mortise and tenon machines. 5. Wide Range of Applications: This kit simplifies the process of drilling square holes in wooden boards. These tools are perfect for construction, woodworking DIY, and the decoration industry, across a variety of materials including compression board, plastic, density board, and various types of wood. Specifications: - Material: Carbide - Product: Square Hole Drill Bit Adapter and Drill Bits - Hand Drill Jig Diameter Range: 38 to 55 mm - Square Hole Drill Bit Sizes: 1/4 inch (6.4 mm), 5/16 inch (8 mm), 3/8 inch (9.5 mm), 1/2 inch (12.7 mm) Package Included: - 1 x Square Hole Drill Bit Adapter - 4 x Square Hole Drill Bits Note: This Square Hole Drill Bit Adapter and Drill Bits set is crafted from enduring carbide material, designed to be versatile, easy to use, and helpful in a wide range of applications. It ensures precision in creating mortises and tenons quickly and effectively, making your woodworking tasks a doddle. It is a must-have for professionals and DIY enthusiasts.