| Company name | Reg. code |
|---|---|
| OSS EST OÜ (former name Amsvp finance OÜ) | 14127974 |
| ESS.O.ESS OÜ | 16004359 |
| OPS EST OÜ | 14571002 |
| ESS.O.ESS KV OÜ | 16158134 |
| ESS KINNISVARA OÜ | 10088800 |
| ESS SOFTWARE OÜ | 17282959 |
| ESS GLOBAL TRADE OÜ | 14609288 |
| JABLANISA TACHLOVANY OÜ (former name OST24 OÜ) | 16198731 |
| BENDER BUREAU OÜ (former name OST Vinyl OÜ) | 16266585 |
| BOLINBENDELEZY KANKUZAK OÜ (former name Balta-Ost OÜ) | 11834240 |
| RAKVERE MOTOKOOLITUSKESKUS OÜ (former name OÜ EumicaR) | 12225514 |