| # | Name | Location | Applications |
|---|---|---|---|
| 1. | O&K Company | 🇯🇵 Higashiosaka-shi, Osaka, Japan | 1 |
| 2. | O&K COMPANY | 🇯🇵 Osaka, Japan | 1 |
| 3. | Ok Capsule, Inc. | 🇺🇸 Reno, NV, United States | 1 |
| 4. | Ok Champion Corporation | 🇺🇸 Hammond, IN, United States | 1 |
| 5. | OK Construction Materials (Supply) Company Limited | 🇨🇳 Hong Kong, China | 1 |
| 6. | OKCHUNDANG CO., LTD. | 🇰🇷 Daegu, South Korea | 2 |