The New Grand Seiko Caliber 9RA5 - Spring Drive 5 Days

Caliber 9RA5. A slim Spring Drive movement with power and strength. Caliber 9RA5's thin profile is made possible by the re-design and re-positioning of the Magic Lever. Developed in-house in 1959, the Magic Lever boosts the efficiency of the automatic winding mechanism by using the energy created by movement of the oscillating weight in both directions. In the new caliber, the new Offset Magic Lever is positioned away from the center of the movement to reduce its thickness. Remarkably, this is achieved with no loss of winding efficiency. The stem and crown are also positioned towards the back of the case to lower the center of gravity and achieve a comfortable fit on the wrist. Caliber 9RA5 may be slim but it has enhanced rigidity and shock resistance thanks to the new layout of the gear train towards the center of the movement and a central bridge that holds them together. This One-piece Center Bridge achieves a shock resistance that meets the ISO standard for diver's watches. Caliber 9RA5 takes Spring Drive technology to a new level of excellence and opens a new era in the history of Grand Seiko. https://www.grand-seiko.com/global-en/special/60th/springdrive5days/