Grand Seiko debuts the Spring Drive UFA Calibre 9RB2 in SLGB001 and SLGB003, offering ±20 sec/year accuracy, Price from €12,000 for the titanium model
Grand Seiko continues its pursuit of timekeeping excellence with the introduction of the Spring Drive Calibre 9RB2, now carrying the new UFA designation. Standing for "Ultra Fine Accuracy," this label marks a new step beyond the VFA, or "Very Fine Adjusted," designation traditionally used to denote movements accurate to within ±1 minute per month.
In contrast, the new Caliber 9RB2 is regulated to an annual accuracy of ±20 seconds. This makes it, according to Grand Seiko’s research as of April 2025, the most precise wristwatch movement powered by a mainspring currently available.
Spring Drive remains one of Seiko’s signature innovations: a hybrid system that combines the mechanical energy of a traditional movement with the precision of a quartz regulator. Like conventional mechanical watches, it is powered by a mainspring that can be wound manually or via a rotor activated by wrist motion.
As the mainspring unwinds, it drives a series of gears that move the hands, while also generating a small electric charge that activates a quartz oscillator and integrated circuit. This mechanism allows the watch to maintain high accuracy without the use of a battery, while ensuring a power reserve of 72 hours.
The exceptional precision of Caliber 9RB2 stems from refined manufacturing and processing techniques applied to the quartz oscillator, which is aged for three months. It also includes a newly developed integrated circuit that operates at extremely low power. Each oscillator is tested at various temperatures, and the circuit is programmed with individual data to ensure optimal thermo-compensation.
To safeguard accuracy and consistency, both the quartz oscillator and its sensor are vacuum-sealed to minimise the impact of humidity, static electricity and light. This protects the regulating components and ensures reliable temperature adjustments over time. Additionally, for the first time in a Spring Drive movement, a regulation switch has been incorporated. This allows technicians to fine-tune the movement during after-sales service to address any minor deviations that may occur over long-term use.
Caliber 9RB2 debuts in two models within the Grand Seiko Evolution 9 Collection.
Reference SLGB003 features a case made of High-Intensity Titanium, which is approximately 30 percent lighter than stainless steel. Reference SLGB001 comes in Platinum 950 and is produced in a limited series of 80 pieces.
Thanks to the movement’s compact architecture, both models are housed in a 37 mm case with a thickness of 11.4 mm. These are the smallest watches to date fitted with a movement from the 9R series. The case showcases Grand Seiko’s renowned Zaratsu polishing, producing a distortion-free mirror finish complemented by refined hairline brushing. Water resistance is rated at 10 bar, equivalent to 100 metres.
Both watches feature box-shaped sapphire crystals with anti-reflective coating on the underside. The textured dials take inspiration from the ice-covered forests of the Kirigamine Highlands, near the Shinshu Watch Studio where the watches are made.
On the SLGB003, the titanium model, the dial is rendered in a silver-toned blue and features a tempered blue seconds hand. The platinum SLGB001 has a deeper blue dial with a silver-toned hand.
Applied indexes with bold grooved profiles and sharply faceted hands ensure excellent legibility, in keeping with the Evolution 9 design philosophy. Both models display the inscription "Spring Drive UFA" at six o'clock, highlighting their exceptional precision.
The movement can be admired through a sapphire crystal case back. The finish includes mirror-polished bevels that reflect the meticulous craftsmanship and the natural surroundings of the Shinshu Watch Studio.
The platinum version is paired with a crocodile leather strap, while the titanium model features a matching bracelet fitted with a new clasp. This micro-adjustable clasp allows for fine sizing in 2 mm increments without tools, offering enhanced comfort.
The Grand Seiko Evolution 9 Spring Drive UFA SLGB003 in High-Intensity Titanium is priced at €12,000. The limited edition SLGB001 in Platinum 950 is offered at €42,000. grand-seiko.com
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