| Brand | Seiko |
| Caliber Number | 9S66 |
| Movement Type | Automatic |
| Jewels | 35 |
| Power Reserve | 72 hours |
| Vibrations Per Hour | 28,800 |
| Hairspring | Spron 610 |
| Shock System | Diashock |
| Features | GMT |
| Country of Manufacture | Japan |
| Known Models | SBGM031 |
The Seiko caliber 9S66 is an in-house movement found in a Grand Seiko GMT Limited Edition. This caliber is essentially an upgrade from GS cal. 9S56 which offered a lower 48 hr power reserve. The 9S66 found in the limited edition GMT has a blue titanium/tungsten rotor featuring a Grand Seiko lion crest.
Additional Resources:
- Read more: Official 9S66 operating instructions from Seiko
- Grand Seiko GMT Anniversary Limited Edition Review
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