Spring Drive 5 Days

Caliber 9RA5

At the birthplace of Spring Drive, the Shinshu Watch Studio, dedicated craftsmen and women meticulously assemble timepieces by hand part by part, from the case, dial, hands and indexes to all other components. At every step of the movement creation process, from development and design to manufacture, assembly, and adjustment, talented and expert craftsmen and women strive for the highest possible standards and maintain their complete dedication to the constant enhancement of their skills. Caliber 9RA5 is the Spring Drive movement that best embodies these skills and their passion.

Caliber 9RA5 has an accuracy rate of ±10 seconds per month and utilizes the Offset Magic Lever to reduce the movement’s thickness by 0.8mm. By moving the position of the crown further back, the watch’s center of gravity is lowered and a perfect fit on the wrist results. The Dual-size Barrels are of differing sizes and arranged to allow for expanded capacity while conserving space. This achieves a 120 hour power reserve. The One-piece Center Bridge guarantees the movement’s strength, durability and shock resistance. Together, these innovative technologies define the next-generation Spring Drive movement, Caliber 9RA5.


Winding mechanism Automatic with manual winding
Accuracy ±10 seconds per month (±0.5 second per day)
Power reserve Approximately 120 hours (5 days)
Number of jewels 38 jewels
Features -Offset Magic Lever
-Dual-size Barrels
-One-piece Center Bridge
-Power reserve indicator

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.