Material: Square hole drill bit adapter bracket is made of aluminum alloy, which is wear resistant and sturdy, ensuring long term performance and reliability Compatibility: Square hole drill bit adapter is suitable for bench drill and hand drill, with a clamp diameter between 38 mm-55 mm/1.5 inch-2.17 inch (the product does not include square hole drill and electric drill) Easy to install: Square hole drill bit adapter fixing bracket, easy to install and remove, no complicated tools required, more convenient to use Widely applicable: Square hole drill fixed bracket is very suitable for woodworking and furniture making, ensuring smooth and accurate drilling Effective: Mortise attachment facilitates drilling suitable mortise and tenon holes in the fastest way, and is a simple and practical tool accessory Specification: Material: Aluminum alloy Size Chart: 5.5 cm/2.17 inch Package Includes: 1x Square Hole Drill Bit Adapter Note: Please allow slightly errors due to manual measurement and different monitors. Note: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement. Sold by-YJL official store