Comes with 1 square hole drill bit adapter and 5 square hole drill bits, drill diameter: 1/4 inch (6.4mm), 5/16 inch (8mm), 7/16 inch (11mm), 1/2 inch (12.7mm) 5/8 inch (16mm) and hand drill clamp diameters range from 38 to 55mm / 1.5 to 2.2 inch (. 5.9cm), easy to install and use; please note it only works with belts Clamps for bench drills and hand drills The square hole drill bit adapter is made of high-quality carbon steel, sturdy and , to hold wood firmly, the length of the drill bit adapter is about 6.3 inches/16 cm, the upper inner diameter is about 0.75 inches/1.9 cm, and the lower diameter is about 2.17 inches/5.5 cm to reduce usage errors, the specially designed tenon accessory drill bit will not be blocked by the wood chip chip, wood chip chip, no rolling, fast cutting speed, sharp drill bit, please take it out safely The drill bit adapter and 5 sizes of matching drill bit attachments are more convenient to use, and the precision design of the drill press mortise attachment ensures you can drill the correct mortises and tenons in the fastest way; more convenient than a mortise machine faster Combines 1 square hole drill bit adapter with 5 square hole drill bits; This layout simplifies the process of drilling square holes on wooden boards; You can reduce your workload with this convenient and simple tool , suitable for beginners and workers; suitable for construction, woodworking DIY, decoration industry, suitable for compressed board, plastic, density board, sandalwood, pine, ash, pine and other materials. low hardness low hardness The wood square hole drill bit is reliable and practical, suitable for bench drills and hand drills; the square hole drill bit adapter is Perfect for woodworking, furniture manufacturing and other related industries. Material: Metal colour: silver Package Contents: 1 x square hole drill bit adapter 5 x square hole drill bits Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.