introduce: It is suitable for hand-held electric drills, vertical electric drilling machines and mobile belt magnetic drilling machines. Professional wood drill bits, suitable for construction, installation, decoration and decoration industries. The utility model uses the impact force of the hammer to transmit the impact force to the outside in the hole drilled by the rotating body. Our drill bits are the first choice for professionals and amateurs, with simple structure and easy operation. The size refers to the length of the square hole drilled by the square hole. Specification: Material: solid hardened steel Color: silver Dimensions: 6mm; 6.4mm; 8mm; 9.5mm; 10mm; 12mm; 12.5mm; 12.7mm; 14mm; 15mm; 16mm; 18mm; 19mm; 20mm; 21mm; 22mm; 25mm; 26mm; 28mm; 30mm; Please note: Tongue and groove set is suitable for wood, medium density fiberboard, particle board, plywood compact board. Please avoid cutting ferrous metals and non-wood materials, such as steel, iron, sand, etc. safety instructions: 1. Blade products are not suitable for people under 18 years of age. 2. Please wear goggles and use ear protection equipment when working. 3. Avoid using your body or clothes close to the tool. Package Contents: 1pc * square hole drill