Grand Seiko Evolution 9 Spring Drive: Breakthrough accuracy of ±20 seconds per year with the 9RB2 movement.

Grand Seiko has officially expanded its Evolution 9 collection with five new Spring Drive models, marking a significant advancement in electromechanical watchmaking technology. The models, codenamed SLGB007, SLGB009, SLGB011, SLGB013, and SLGB015, are expected to be available from September 2026, promising to set a new standard for accuracy in the Spring Drive movement.

Power from the 9RB2 movement and UFA standard.

The most important technical highlight of this product line is the Caliber 9RB2 movement. This is a Spring Drive movement that meets the UFA (Ultra Fine Accuracy) standard, which Grand Seiko introduced last year. Unlike the purely mechanical Hi-Beat 9SA5 movements, the 9RB2 combines mainspring power with the electronic control system characteristic of Spring Drive.

In terms of performance, the Caliber 9RB2 achieves astonishing accuracy with an error of only ±20 seconds per year. This is a remarkable figure for any mainspring-driven movement. However, to achieve this extremely high accuracy, Grand Seiko has made a trade-off in power reserve. Instead of the 5 days (120 hours) of previous Spring Drive Evolution 9 movements, the 9RB2 offers a power reserve of 72 hours.

Ergonomic design and premium materials

Of the five new models, four versions (SLGB007, SLGB009, SLGB011, SLGB013) use a 40 mm case size, 11.7 mm thickness, and a lug-to-lug distance of 47.2 mm. Most notably, the SLGB015 model features a smaller case size of 37 mm, 11.4 mm thickness, and a lug-to-lug distance of 44.3 mm. This is an optimal choice for users with smaller wrists, who often find the standard size of the Evolution 9 series somewhat large.

In terms of materials, the SLGB007 model is crafted from High-Intensity Titanium, offering lightweight construction and superior scratch resistance. The other four models utilize Ever-Brilliant Steel, a material with a high gloss finish and better corrosion resistance than conventional stainless steel.

The dial art is inspired by nature, Shiojiri.

Continuing the tradition, the dial designs of the new models are inspired by the natural landscape surrounding the Shinshu Watch Studio in Shiojiri, Nagano:

• SLGB007:The dark, textured dial mimics the image of Lake Suwa at night.
• SLGB009:The distinctive "White Birch" pattern is featured on Ever-Brilliant steel.
• SLGB011:Recreating the green color of the river in the Atera Valley.
• SLGB013 and SLGB015:Utilize the blue hues of Lake Suwa with shells of varying sizes.

All five models come with a slim strap and a new generation three-step micro-adjustment clasp. The crystal is a box sapphire with an anti-reflective coating on the inside. Additionally, the watches feature a power reserve indicator and are water-resistant to 10 bar (100 meters).

Detailed specifications

These watches will be distributed through Grand Seiko's boutique network and select retail partners worldwide starting in September 2026. The official price in the US market has not yet been confirmed.