The Grand Seiko SLGB009 and SLGA009 are both 40 mm Evolution 9 Spring Drive watches with White Birch-inspired dials, but their movements make them distinct. The SLGB009’s Caliber 9RB2 is rated by Grand Seiko at ±20 seconds per year and runs for about 72 hours; the SLGA009’s Caliber 9RA2 is rated at ±10 seconds per month and runs for about 120 hours. Both measure 40.0 mm across, while the SLGB009 is slightly shorter lug-to-lug and thinner on the published dimensions.
At a glance: SLGB009 vs. SLGA009
| Specification | SLGB009 | SLGA009 |
|---|---|---|
| Collection and movement designation | Evolution 9; Spring Drive U.F.A. | Evolution 9; Spring Drive 5 Days |
| Caliber | 9RB2 | 9RA2 |
| Movement | Spring Drive, automatic with manual winding | Spring Drive, automatic with manual winding |
| Stated accuracy | ±20 seconds per year; also shown by Grand Seiko as ±3 seconds per month | ±10 seconds per month; also shown as ±0.5 second per day |
| Approximate power reserve | 72 hours, or about 3 days | 120 hours, or about 5 days |
| Diameter | 40.0 mm | 40.0 mm |
| Lug-to-lug | 47.2 mm | 47.9 mm |
| Thickness | 11.7 mm | 11.8 mm |
| Case and bracelet material | Ever-Brilliant Steel | Stainless steel |
| Water resistance | 10 bar | 10 bar |
| Magnetic resistance | 4,800 A/m | 4,800 A/m |
| Weight | 168 g on Grand Seiko’s Japanese official listing; omitted on the English regional listing | 176 g on Grand Seiko’s official listing |
Specifications are from Grand Seiko’s SLGB009 product page, SLGA009 product page, and January 11, 2022 brand news page. The product pages do not show a publication year for their specifications.
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How the movements and accuracy ratings differ
SLGB009: Caliber 9RB2 and U.F.A.
Grand Seiko calls the SLGB009’s Caliber 9RB2 Spring Drive U.F.A., defining U.F.A. as “Ultra Fine Accuracy.” The product page gives a rating of ±20 seconds per year and also expresses it as approximately ±3 seconds per month. Its listed power reserve is about 72 hours. The annual rating is the defining accuracy claim for this model.
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The SLGA009’s Caliber 9RA2 is rated at ±10 seconds per month, also expressed as ±0.5 second per day, and has an approximately 120-hour reserve. Grand Seiko says the movement measures temperature 540 times per hour to compensate for variations in oscillator performance. The brand’s January 11, 2022 announcement gives the SLGA009’s 120-hour reserve and monthly accuracy specification.
#1 Best Overall
- Calendar-linked time difference adjustment function
- Movement Caliber 9S86,
- Dual-curved sapphire crystal
How to interpret the figures
These are manufacturer specifications reported over different periods, not results from a shared independent comparison test. The annual and monthly ratings should not be treated as directly measured head-to-head results or as a guarantee of each wearer’s day-to-day timekeeping. Actual performance under an individual’s wearing and environmental conditions is not established by these published figures.
Case size and wrist fit
Both watches have a published 40.0 mm diameter. The SLGB009 is 47.2 mm lug-to-lug and 11.7 mm thick, compared with 47.9 mm and 11.8 mm for the SLGA009. Those figures make the SLGB009 modestly shorter and thinner on paper; the difference is small, and dimensions alone do not establish which watch will feel better on a particular wrist. Wrist shape, bracelet adjustment, and personal preference also affect fit.
Rank #2
- Three-fold clasp with push button release
- Dual-curved sapphire crystal
- Power reserve display on the back
- Power resrve Approx. 72 hours(3 days)
White Birch design and materials
Grand Seiko connects both models to the white birch forests near the Shinshu Watch Studio. The SLGB009 page describes an intricate dial pattern and identifies Ever-Brilliant Steel for its case and bracelet. The SLGA009 page describes a white-birch dial and a stainless-steel case. Grand Seiko’s announcement describes the SLGA009 dial as an interpretation of the birch inspiration; the shared theme does not mean the dials are identical.
Quick Recap
Best Value
- STUNNING BLUE DIAL: this automatic men's watch features a deep blue, pressed pattern and gloss finish surrounded by a stainless steel watch case
- AUTOMATIC: these self-winding, automatic men's watches are powered by your movement, with a power reserve of 41 hours
- STAINLESS STEEL: features a durable stainless steel watch case and bracelet with see through caseback
- WATER-RESISTANT: these men's wrist watches are water-resistant down to 50 meters
- 4R35 CALIBER: equipped with the reliable caliber 4R35 automatic movement, this accurate men's watch keeps precise time
Rank #4
- BURGUNDY DIAL: this men's automatic watch features a burgundy deep, pressed pattern with a gloss finish and rose gold stainless steel watch case
- AUTOMATIC: these self-winding, automatic men's watches are powered by your movement, with a power reserve of 41 hours
- STAINLESS STEEL & LEATHER: features a durable rose gold-finish stainless steel watch case paired with a brown leather watch band
- WATER-RESISTANT: these men's wrist watches are water-resistant down to 50 meters
- 4R35 CALIBER: equipped with the reliable caliber 4R35 automatic movement, this accurate men's watch keeps precise time
Rank #3
- See-through case back
- Date display
- Screw-down crown
- 40mm Diameter
- Weight 178.0 g
Which model fits your priorities?
- For the annual-accuracy specification: the SLGB009’s 9RB2 carries Grand Seiko’s ±20-seconds-per-year U.F.A. rating.
- For a longer listed reserve: the SLGA009 offers about 120 hours, versus about 72 hours for the SLGB009.
- For the slightly smaller published footprint: the SLGB009 is 0.7 mm shorter lug-to-lug and 0.1 mm thinner, with the same 40.0 mm diameter.
- For water and magnetic resistance: the published specifications are the same—10 bar and 4,800 A/m, respectively.
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