Automatic Spring Drive 3-Day GMT
Caliber 9R66
In 2006, just two years after the completion of Caliber 9R65, Grand Seiko's first 9R Spring Drive movement with a GMT (Greenwich Mean Time) function, Caliber 9R66, was unveiled.
Specifications
| Winding mechanism | Automatic with manual winding |
|---|---|
| Accuracy | ±1 second per day (±15 seconds per month) |
| Power reserve | Approximately 72 hours |
| Number of jewels | 30 jewels |
| Features | -Power reserve indicator
-Dual time function with 24-hour hand -Quick correction function of time difference adjusting to a calendar |
What makes 9R Spring Drive special?
Spring Drive, one of the great innovations in modern watch making history, regulates a spring-driven movement with state-of-the-art electronic technology that functions without batteries or other external power source. Its sole power source is a mainspring, which drives a series of gears. A rotor, connected to the end of these gears, generates a small electrical charge that activates an electronic circuit and quartz oscillator. Its accuracy is unprecedented for a watch wound by a mainspring. The development of the 9R Spring Drive movement was possible only because Grand Seiko is one of the few manufacturers with expertise in both mechanical and electronic watches.
