Specific usage method: 1. Since the chuck has many gaps, you need to check the residue in the gaps of the chuck and clean the chuck with petrol or detergent before installing the tools. 2. Chuck and plug socket are mounted together on the spindle of the machine tool. Mount chuck on the shaft cone bore, tension spring carefully turn, press the plug socket into the chuck groove and press chuck evenly. 3. After cleaning, insert the additional handle of the tool into the clamping hole. After making sure that the chuck is aligned with the tool, tighten the plug socket until the tool is clamped before use. 4. If you need to replace the chuck, loosen the chuck and remove the chuck and cutter to replace other chucks. Specifications: material: carbon steel. Package includes: 2 x 6 mm engraving machine chuck 2 x 6.35 mm engraving machine chuck 2 x 8 mm engraving machine chuck 1 x 7 mm nut 1 x 8.5 mm nut