Grand Seiko Once Again Raises the Bar for Mechanical Timekeeping

Seiko exponentially improves the accuracy of the world’s most respected mechanical watch movement.

Silver metal wristwatch with textured white dial, blue second hand, date window, and linked bracelet band.

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By Brad Lanphear

Published December 26, 2025

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They say true beauty is found within.

Grand Seiko’s SLGB003 is a beautiful watch, but nothing about its appearance stands out from the rest of the brand’s Evolution 9 collection.

Look inside the case, however, and you’ll find one of the most remarkable mechanical watch movements ever devised: the caliber 9RB2 Spring Drive Ultra Fine Accuracy.

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Grand Seiko watch movement with visible jewels and "Spring Drive Ultra Fine Accuracy" engraving. — Grand Seiko outdoes itself with the caliber 9RB2 Spring Drive Ultra Fine Accuracy movement.

Grand Seiko’s Spring Drive movement achieved a nearly mythical status among watch enthusiasts for blurring the line between mechanical and quartz timekeeping. While it is technically an automatic movement with no battery involved, it utilizes quartz crystals to regulate time with an astonishing accuracy of +/-15 seconds per month.

In 2025, Grand Seiko’s Spring Drive UFA made a quantum leap in horological engineering by shattering the previous accuracy with a measurement of +/-20 seconds per year. Most battery-powered quartz movements don’t even come close to that mark.

Silver stainless steel Grand Seiko wristwatch with textured silver dial and blue second hand. — The Grand Seiko SLGB003 has a 37mm High-Intensity Titanium case.

According to Grand Seiko, this astonishing improvement in mechanical movement regulation was accomplished by refining the growth and processing of the three-month-aged quartz oscillator at the heart of the design.

Additionally, the integrated circuit — another aspect borrowed from quartz movement design — has been improved, and the entire regulation system is vacuum-sealed to prevent interference.

a grand seiko watch on a mans wrist — The Spring Drive UFA movement is also available in the platinum-cased caliber SLGB001.

Barring any last-minute surprise releases, 2025 will mark the release of the first three Spring Drive UFA-powered watches, all of which are 37mm members of the Evolution 9 Collection.

The movement debuted in April with the titanium SLGB003, alongside the limited-edition SLGB001, which featured a platinum case and alligator leather strap. Then the SLGB005, sporting a deep violet Kirigamine dial, was released in September.