Grand Seiko SLGB001 & SLGB003: 37mm case, Spring Drive U.F.A. movement, and a micro-adjustable bracelet
Zach BlassI wish Grand Seiko would make a micro-adjustment clasp. I wish Grand Seiko would make smaller Spring Drive watches. For years, Grand Seiko fans have begged and pleaded, and today is the day these wishes have been granted in one fell swoop, all in the name of Watches and Wonders 2025. Meet the new Grand Seiko SLGB001 and SLGB003 Ice Forest duo. Pretty much everything about these watches is new, the only exceptions being the Evolution 9 case geometry and shape of dial elements. The dimensions, dial texture, Spring Drive calibre, and bracelet are all brand new. There is so much to cover here, but let’s dig into the marquee element of this release – at least in the eyes of Grand Seiko fans – the new micro-adjustment clasp.
A new micro-adjust bracelet!
The SLGB001 is a platinum-cased limited edition on a leather strap, but the titanium variant, the SLGB003, is a regular-production, high-intensity titanium model outfitted on a case-matching bracelet. Though the bracelet format remains the familiar brushed five-link, moving down towards the clasp you will see something new. Grand Seiko certainly took its time in the creation of this micro-adjustment clasp, but the wait appears to be worth it.
Despite criticisms being thrown at Grand Seiko bracelets by some, one thing I always appreciated on all of my Grand Seikos is that the clasps do not add bulk to the bracelet. This new clasp adds basically zero thickness to the bracelet, and now offers 6mm of on-the-fly micro-adjustment across three increments of 2mm.
The cases
The only catch is that this clasp is being rolled out on a bracelet of a new scale, suited strictly for the debuting 37mm case that clocks in at 11.4mm thick – akin to the larger 38mm and 40mm Evolution 9 designs. It is also worth quickly noting it is still 100 metres water-resistant, and that the finishing style remains the same, with the cases alternating between Grand Seiko’s immaculate hairline brushed and Zaratsu distortion-free, mirror-polished surfaces. But to get this out of the way, it is my understanding that this clasp currently exists strictly for the SLGB003 and that the clasp cannot be purchased separately – and even if you could, it won’t be compatible with older models like the Shunbun or Snowflake anyway. In due time, though, it would seem the rollout of this new clasp into other sizes of bracelets is inevitable.
The movement
Though there have been smaller Seiko Corporation Spring Drive watches in the past, the fact we have the first 9R-series Grand Seiko in a 37mm diameter is thanks to a new calibre: the 9RB2. Though it is smaller, the other big headline is that this is a more accurate movement than its larger siblings, whether the standard, three-day 9R65 or even the latest-gen 9RA2 movement. Admittedly, we’re splitting hairs here, because at a minimum the 9R65 is billed to be accurate within 15 seconds per month, and the 9RA2 within 10 seconds per month. This new 9RB2, however, debuts Grand Seiko Ultra Fine Accuracy and, as a U.F.A. Spring Drive Calibre, it is billed to be accurate within 20 seconds per year – six times more accurate than the 9RA2.
U.F.A. is an evolution of V.F.A. (Very Fine Adjustment), which debuted in 1969, and vintage mechanical Grand Seiko watches that bore this stamp were pledged to run within just one minute per month – effectively two seconds per day. This was on par, if not superior, to anything that Switzerland made at the time, and still more than holds up to this day. To wrap up the accuracy conversation, this new 9RB2 movement, according to Grand Seiko’s research, is the most accurate wristwatch movement powered by a mainspring today. As a brand driven by precision, this is a title I am sure Grand Seiko is happy to hold. Aesthetically speaking, the 9RB2 shares visual cues first seen on the five-day 9RA2 movement, also elegantly decorated with the delicate Shinshu frost finish on its bridges and mirror-bevelled edges on the bridges and openworked winding rotor. You will also notice a movement-side power reserve indicator with a small, heat-blued hand.
The dial
Normally when I review Grand Seiko watches, the dial is the first thing I would talk about, but in this instance it’s the aspect we’ll end on. Both the platinum SLGB001 and titanium SLGB003 debut a new “Ice Forrest” texture. It has a prismatic feel to it, inspired by the frost-covered trees in the highlands to the east of the Shinshu Watch Studio where Spring Drive watches are made – seemingly perfectly manicured by mother nature with a sharp triangular look.
The titanium SLGB003 debuts this new pattern with a silver dial that has the slightest blue tint, while the platinum SLGB001 is executed in a much clearer icy blue. This explains why Grand Seiko has elected to blue the central seconds hand on the SLGB003, and not on the SLGB001. The dial will otherwise feel familiar in layout, with the Evolution 9 broad hours hand and hour index shape. You also have a standard black-on-white date at the 3 o’clock position, with the U.F.A. branding subtly, but proudly displayed above the 6 o’clock index.
The verdict
Overall, I think Grand Seiko fans are going to be very, very happy with this new release. I am a Grand Seiko fan, and I know I am thrilled to see various evolutions I have long asked the brand for come to fruition all at once. The only point of criticism I suspect will come out of this is that this new micro-adjustment clasp is debuting on a 37mm model and not a 40mm model. Though it means those not interested in mid-sized Grand Seiko will have to wait longer, I think it is wise that they debuted this new clasp in a new size where they can have an easier time with an inaugural rollout and not get swamped with requests to purchase the new clasp. It is not my intention to overshadow the platinum SLGB001; it’s a stunning watch, but it is limited to 80 pieces, and naturally priced much higher at US$39,000 due to its precious metal case. With these watches hitting shelves in June 2025, I suspect most will be working to set aside US$10,900 to try and secure the titanium SLGB003.
Grand Seiko Evolution 9 Spring Drive U.F.A. Ice Forest SLGB001 & SLGB003 pricing and availability
The Grand Seiko SLGB003 and SLGB001 will be available for purchase beginning June 2025. Price: US$10,900 (SLGB003), US$39,000 (SLGB001, limited to 80 pieces)
| Brand | Grand Seiko |
| Model | Evolution 9 Spring Drive U.F.A. |
| Reference | SLGB001, SLGB003 |
| Case Dimensions | 37mm (D) x 11.4mm (T) |
| Case material | 950 platinum (SLGB001) High-intensity Titanium (SLGB003) |
| Water Resistance | 100 metres, screw-down crown |
| Crystal(s) | Sapphire front and back |
| Dial | Blue (SLGB001) Silver (SLGB003) |
| Bracelet and strap | Crocodile leather, three-fold 950 platinum and 18k white gold clasp (SLGB001) High-intensity titanium bracelet, three-fold clasp, micro-adjust (SLGB003) |
| Movement | 9RB2, in-house, automatic, Spring Drive |
| Power Reserve | 72 hours |
| Functions | Hours, minutes, seconds, date, power reserve (movement side) |
| Availability | June 2025, SLGB001 limited to 80 pieces |
| Price | US$39,000 (SLGB001) US$10,900 (SLGB003) |