| Sr# | Company | Standard | Certificate Number |
| 631 | Minerals Chemicals Factory | ISO 9001:2008 | 100CN157142258 |
| 630 | Optimum Engineering Standards Co. Ltd. | ISO 18001:2007 | 300CN150922254 |
| 629 | Optimum Engineering Standards Co. Ltd. | ISO 14001:2004 | 500CN150902252 |
| 628 | Optimum Engineering Standards Co. Ltd. | ISO 9001:2008 | 100CN157122250 |
| 627 | Al Howail Wood Works Factory | ISO 9001:2008 | 100CN157112240 |