| Company name | Reg. code |
|---|---|
| QHS OÜ | 16674226 |
| QHS CERTIFICATION OÜ | 17402895 |
| QHS-POWER SOLUTIONS OÜ | 17147256 |
| QHSE CONSULTING OÜ | 16134895 |
| BHS OÜ | 16178025 |
| FHS OÜ | 12616278 |
| OHS OÜ | 10116940 |
| QOS OÜ | 17141762 |
| 3QWS OÜ | 14632399 |
| GHS OÜ | 14841826 |
| MHS OÜ (former name GOOD OÜ) | 12482079 |
| QPS OÜ kustutatud | 12782963 |
| QMS OÜ | 11404410 |
| NHS OÜ | 14769655 |
| EHS OÜ | 17227647 |
| QHP123 OÜ (former name Q-haus Prefab OÜ) | 14612959 |
| HHS OÜ | 12598735 |
| CHS OÜ | 12843034 |
| QRS OÜ | 14487997 |
| KHS OÜ | 16122403 |
| QLS OÜ (former name QLS AS) | 11299278 |
| THS OÜ | 12827360 |
| RHS OÜ | 14859743 |
| KHS MÍDIA OÜ | 16703073 |
| AHS GROUP OÜ | 14433263 |
| OHS SERVICES OÜ (former name Honkatalot PLH Group OÜ) | 14717871 |
| NHS TEENINDUS OÜ | 17142603 |
| NHS HOLDING OÜ | 16655051 |
| NHS PARTNER OÜ | 16728933 |
| NHS KAPITAL OÜ | 16678494 |
| QMS DRILLERS OÜ kustutatud | 12627780 |
| HQS DEVELOPMENT OÜ | 14359845 |
| MHS YHTIÖT OÜ kustutatud (former name 321Innovaatiot OÜ) | 14028692 |
| MHS REKLAAM OÜ | 12530097 |
| BHS PRAXIS OÜ | 16884142 |
| DHS KESKUS OÜ | 12540664 |
| NHS MOTORS OÜ | 16663205 |
| NHS GRUPP OÜ (former name Dubrovski OÜ) | 16447424 |
| NHS INVEST OÜ | 16627971 |
| DHS BALTICS OÜ kustutatud (former name Frontmen OÜ) | 12923715 |
| NHS EXPORT OÜ | 17143258 |
| DHS MEEDIA OÜ | 14585547 |
| PHS BALTIC OÜ kustutatud | 12564156 |
| EHS INVEST OÜ | 16242521 |
| THS CAPITAL OÜ | 14932842 |
| MHS TRADE OÜ kustutatud | 12086159 |
| LEMBITU LHS OÜ (former name OÜ Supelus) | 12155512 |
| QBS TRADING OÜ | 12872610 |
| MHS TRADE OÜ | 17081304 |
| THS ELEKTROONIKA OÜ | 10089283 |