| 571 | Oil Rig Builders | Company Product |
| 572 | Oil Pumps | Company Product |
| 573 | Oil Purifiers | Company Product |
| 574 | Oil Proof Packings | Company Product |
| 575 | Oil Hardening Tool Steel | Company Product |
| 576 | Oil Handling Equipment | Company Product |
| 577 | Oil Field Part Machining | Company Product |
| 578 | Oil Field Services | Company Product |
| 579 | Oil Field Equipment | Company Product |
| 580 | Oil Exploration Equipment & Supplies | Company Product |
| 581 | Oil Exploration Companies | Company Product |
| 582 | Oil Discharge Monitoring & Control Systems | Company Product |
| 583 | Oil Drilling Bits | Company Product |
| 584 | Oil Cooler Repair | Company Product |
| 585 | Oil Companies | Company Product |
| 586 | Oil Companies' Supplies | Company Product |
| 587 | Oil Casing | Company Product |
| 588 | Oil Bunkering | Company Product |
| 589 | Oil Absorbers | Company Product |
| 590 | Oil Bottles | Company Product |
| 591 | Oil & Gas Well Screens | Company Product |
| 592 | Offset Printing | Company Product |
| 593 | Offshore Cranes | Company Product |
| 594 | Offshore Rubber Products | Company Product |
| 595 | Ohmmeters | Company Product |
| 596 | Offset Plate Making | Company Product |
| 597 | Offset Printing Machines | Company Product |
| 598 | Offshore Equipment & Supplies | Company Product |
| 599 | Office Supplies | Company Product |
| 600 | Office Space Rental | Company Product |