1. Single nickel-chromium-nickel silicon WRN-621 2. Single NiCr-NiSi WRN-621A 3. Double NiCr-NiSi WRN2-621 4. Single nickel-chrome-copper nickel WRE-621 5. Single nickel-chrome-copper nickel WRE-621A 6. Double Nickel Chrome-Copper Nickel WRE2-621 7. Single NiCr-NiSi WRN-631 8. Double NiCr-NiSi WRN2-631 9. Single NiCr-CuNi WRE-631 10. Double NiCr-CuNi WRE2-631 TAG：