Caliber 9R01 is a manual-wound movement based on Seiko's Spring Drive technology.
All Spring Drive movements already offer a remarkable 72 hours of power reserve, but this was extended for caliber 9R01. To maintain perfect timekeeping for up to eight days (192 hours) requires greatly increased power, which is provided by a linked series of three barrels. This remarkable caliber, 9R01, has also been designed throughout to maximize energy efficiency, reducing friction between parts that would otherwise lead to loss in the transmission of the energy derived from the mainspring.
Spring Drive is a unique watch technology. It generates energy like every other luxury mechanical watch but combines this with an electronic regulator to deliver a level of precision that no mechanical watch can match.
The development of Spring Drive was possible because Grand Seiko is one of the very few manufacturers with mastery of both electronic and mechanical watchmaking.