1. Baker Hughes Company
2. Barbco Inc.
3. Charles Machine Works Inc.
4. Creighton Rock Drill Ltd.
5. Direct Horizontal Drilling Inc.
6. Drillto Trenchless Co. Ltd.
7. Ellingson Companies
8. Ferguson Michiana Inc.
9. Halliburton Company
10. Helmerich & Payne Inc.
11. Herrenknecht AG
12. Horizontal Technology Inc.
13. Laney Directional Drilling Co.
14. Mccloskey International
15. McLaughlin Group Inc.
16. Nabors Industries
Ltd.
17. National Oilwell Varco Inc.
18. Prime Drilling GmbH
19. Schlumberger Limited
20. Scientific Drilling International Inc.
21. Toro Company
22. Tracto Technique GmbH & Co. KG
23. Vermeer Corporation
24. Weatherford International PLC
25. XCMG Group