Mortising Attachment for Drill Press The adapter is designed for bench and hand drills that use a clamped round diameter bearing. The round chuck diameter should be 38 to 55 mm (1.5 to 2.2 inches) and the clamping bearing width should be at least 0.48 inches (12 mm). Versatile DualUse Design Easily switch between table drills and hand drills. This design is suitable for woodworking enthusiasts and professionals in furniture making and related industries. Bench Drill Mortise Accessories The mortise converter is easy to install and remove. You can quickly install or remove it yourself, saving time and effort. Material The square hole drill fixed bracket is made of all steel casting, providing sturdy performance. If stored in a humid environment for a long time, some surface rust may occur, which can be improved by wiping with protective oil. Product name Square Hole Drill Bit Adapter