The new Grand Seiko Spring Drive UFA SLGB001 & SLGB003 (With Finally a Micro-Adjustment Clasp)

When talking about vintage Grand Seiko watches, some references or acronyms have a lot of meaning. For instance, 44GS refers to one of the most important models ever, the watch that initiated the Grammar of Design and the shape of all subsequent creations. The acronym VFA also has its importance. Standing for Very Fine Adjusted and first used in 1969, this designation defined a Grand Seiko watch that was adjusted so skillfully that it achieved an astonishing monthly rate of ±1 minute. Now, Grand Seiko has turned part of its production to the Spring Drive technology, a hybrid system known for its great accuracy. This year, with the Evolution 9 Spring Drive SLGB001 & SLGB003, a new acronym is introduced: UFA, standing for Ultra Fine Accuracy and announcing a new generation movement, Calibre 9RB2. But that’s not all, as this duo of compact and handsome watches also comes with the long-anticipated micro-adjustment folding clasp. 

The handsome Evolution 9 SLGB001 & SLGB003

Before we dive into the important details regarding the movement and the very reason why this watch carries the new UFA – Ultra Fine Accuracy – name, let’s have a look at what they look like – after all, a watch should first and foremost look good, feel good and wear good.

These new models are part of the Evolution 9 collection and should be seen as the “smaller sisters” to the White Birch Spring Drive SLGA009. Indeed, not only the proportions are different, but the movement is also meant to be more compact and doesn’t feature some of the refinements of the Calibre 9RA2, such as the double-barrel and 5 days (120 hours) power reserve allowed by the larger diameter. Regarding the overall shape, the new titanium SLGB003 and platinum SLGB001 come with the familiar, more modern and sleeker design cues of the Evolution 9 collection, only now in smaller cases. This design should be seen as a continuation of the Grand Seiko Style that reaches back to the iconic 44GS of 1967 – which includes more brushed areas with Zaratsu polished accents, a lower centre of gravity and a more balanced feel on the wrist.

What matters besides the shape and finish are the proportions. This duo, nicknamed “Ice Forest” (you’ll see why when we talk about the dials), comes in cases measuring 37mm in diameter, in line with the current trend for smaller watches. Additionally, fans of the brand will be happy to see that, despite the presence of a box-shaped sapphire crystal, a screwed caseback with see-through sapphire and a comfortable 100m water-resistance, the watches are decently thin at 11.4mm. For comparison, a Snowflake with the previous-generation Calibre 9R65 is 12.5mm in thickness and a Shunbun Spring Drive SBGA413 with the same movement is 12.8mm… incremental improvements.

Two versions of the Evolution 9 Spring Drive UFA have been released. First is the reference SLGB003, a classic for the brand worn on a metal bracelet, and made out of High-Intensity Titanium, comparable to grade 5 titanium even though being said to be a proprietary alloy. The latter is equipped with a screw-down crown, a pleasant feature on such a daily-oriented watch. Then is the reference SLGB001, a high-end limited edition made of 950 platinum and worn on a leather strap. This version is entirely identical to the titanium model in shape and finish, and despite not having a screw-down crown, it retains a 100m water-resistance.

In addition to these new proportions and a reworked design for the case, the Evolution 9 Spring Drive UFA models also introduce a new dial pattern – a speciality of Grand Seiko, with proper home runs such as the White Birch, the Snowflake, the renewed Mount Iwate or the Genbi Valley (to name a few). Named Ice Forest, it depicts the tips of frost-covered trees as observed during harsh winter months, next to the Shinshu Watch Studio and the Kirigamine Highlands. The intricately textured dials of both creations “capture the beauty of these ice forests thanks to finishing techniques that create pale blue tones.”

Some differences can be seen depending on the version. The titanium SLGB003 version has a silver-tinged blue hue (almost imperceptible in certain angles), combined with a tempered blue seconds hand. The platinum SLGB001 model has the same pattern but this time with a slightly deeper blue colour, this time combined with a silver-coloured seconds hand. On both, the dial uses the Evolution 9 bold hands and grooved hour markers – identical in shape to a White Birch – with a framed date window, and an applied GS logo but no lume to be found.

The new UFA-rated Calibre 9RB2

Now that we’ve talked about design, let’s move on to the mechanics. Before, let’s rewind a bit and remind us about the Spring Drive technology. An in-house development of the Seiko Corporation, it relies on a movement that is 90% mechanical (and for most, automatic), including storage of energy in a classic barrel, with the traditional regulating organ replaced by a quartz-driven oscillator, adding superior accuracy. The Spring Drive technology was developed during the late 1970s and early 1980s, and became a commercial reality in 1999 inside a Seiko watch. In 2004, Grand Seiko introduced the Spring Drive Calibre 9R65, which has become its go-to base movement ever since. In 2005, the brand released the Snowflake SBGA011 (later SBGA211), which popularized the concept. With this generation of movements, the accuracy is rated at ±15 seconds per month.

In 2020, Grand Seiko introduced the Calibre 9RA5, a new generation of Spring Drive movements with a slimmer profile, more power, new electronics with improved accuracy and more refined finishing with the signature frosted surfaces. This generation of movements upgraded the monthly accuracy to ±10 seconds.

Using the knowledge gathered with the Calibre 9RAx generation of movements, Grand Seiko now introduces the Calibre 9RB2, opening a new generation of movements with the UFA standard – or Ultra Fine Accuracy, a node to the VFA Very Fine Adjusted name printed on the top-of-the-range vintage watches of the brand. This impressive movement now boasts an even finer accuracy which isn’t defined in seconds per day, week, or month, but by its accuracy over one year. The automatic UFA Calibre 9RB2 has an astounding rate of ±20 seconds per year (approximately ±3 seconds per month), making it “the most accurate wristwatch movement powered by a mainspring today,” to quote the brand (as of April 2025, based on Grand Seiko’s research).

This even finer accuracy is achieved thanks to new and enhanced manufacturing and processing methods for the three-month-aged quartz oscillator and a newly designed IC. The frequency of each individual quartz oscillator is measured at several different temperatures, with the resulting data necessary for thermo-compensation programmed into the low-power IC. Both the oscillator and sensor are vacuum-sealed to minimize temperature differences and protect against external factors such as humidity, static electricity, and light, ensuring precise temperature adjustments and the stable performance of the quartz oscillator. In addition, for the first time in Spring Drive, the new movement features a regulation switch that can be used during after-sales service to correct any divergences in accuracy that may occur over long periods of use – thanks to a screw visible on the back.

This movement is compact and aims to replace the 9R6x generation of automatic calibres with a 3-day power reserve. It is 30mm in diameter and 5mm in thickness (vs. 5.8mm for a classic 9R65) and only relies on a single barrel. It still has a 72-hour power reserve – which can be controlled via an indicator on the back. The idea is to have a smaller, slimmer movement that will later be adapted to more compact watches such as possibly the 62GS collection, improving the thickness of their profile. The back reveals the signature finishing of the Shinshu Watch Studio, with frosted plates and bridges bringing contrast to the polished bevelled edges.

The long-awaited micro-adjustment clasp

And we’ll finish this article with possibly the best news – at least, considering the requests of the Grand Seiko community… There is indeed a micro-adjustment system on the folding clasp of the Grand Seiko Evolution 9 Spring Drive UFA SLGB003 in titanium. Yes, it is here and it is great.

As you can see, no more butterfly clasp or non-adjustable classic folding clasp here, but a brand new two-fold clasp with a comfort release device. Also made of High-Intensity Titanium, this new – and decently-sized (it’s a bit thicker and longer, but that is to be expected with this device) – clasp integrates an on-the-fly three-step micro-adjustment system that operates without a tool, allowing precise adjustments in 2mm increments for enhanced comfort. It also features a push button release for added safety.

How does it work? In all fairness, it is simple, easy and straightforward. Open the clasp, lift the internal element to a 90-degree position, glide backwards or forward to the desired increment, put back the flipping element in place and voila. No need for more, it is simple and does the job you’d expect from a micro-adjustment clasp. And now, we’re really looking forward to seeing it on more watches from Grand Seiko.

As for the general comfort of these new Grand Seiko Evolution 9 Spring Drive UFA Ice Forest SLGB001 & SLGB003 models on the wrist, and in particular the titanium edition, it’s a joy… Compact, light, balanced and relatively thin, these combine the sporty, sharp looks of a GS watch with a certain elegance coming from the restrained dimensions. Also, compared to the larger White Birch watches, the bracelet slightly tapers, making it more elegant.

Availability & price

Available from June 2025, the titanium SLGB003 will be part of the permanent collection and priced at EUR 12,000, from Grand Seiko Boutiques and select retail partners worldwide. The platinum SLGB001, priced at EUR 42,000, is limited to 80 pieces and exclusive to the Grand Seiko Boutiques. For more details, please consult www.grand-seiko.com.