Two-Pack Square Hole Drill Bit Adapters, Drill Holders, Professional Accessory Adapters, Insert Drills [High-Quality Materials]: The square hole opening holder is made of solid aluminum and is wear-resistant, tough, durable, and... [Efficient and Practical]: Professional woodworking tools: The square hole drill bit adapter holder allows you to drill square holes in seconds, significantly improving woodworking efficiency and serving as a powerful aid in woodworking. [Easy to Use]: This tool makes opening square holes easy. You can quickly assemble and disassemble it yourself. It is fast and convenient, and even beginners can get started without any problems. [Universal Design]: All square hole drill bits are universally compatible and suitable for 38-43 mm chucks of electric drills. The clamping diameter is standardized at 19 mm, enabling precise and consistent drilling. [Wide Application]: Professional woodworking tools: Most hand drills can be used with this holder; however, cordless drills (lithium series) and bench drills are not suitable. Precision square hole drilling tools are suitable for creating mortise and tenon joints and slots for a secure connection. Color: Silver Material: Aluminum Package includes: 2 x Square Hole Drill Holder Only the above package contents are included; other products are not included. Note: Light reflections and different display settings may cause the color of the item pictured to differ slightly from the actual product. The allowable measurement deviation is +/- 1-3 cm.