Metal, Metals Mixed, 1. To weld bolts exactly to holes in panels 2. To project thread not being burned by electric current(Insulated protection) 3. Product Characteristic:High insulating resistance, Super anti abrasive capability, and Anti oxidation at high temperature & Anti thermal shock. 4. Each guide bushing could weld 8000~10000pcs nuts/studs. 5. Compared with KCF material, DIP material is quality guaranteed, low cost and short lead, Hardware Fasteners ...