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：