Vintage Seiko 5 Actus SS 23 jewel mechanical watch, from November 1974

Seiko vintage mechanical watch
MADE IN JAPAN

“Seiko” (精工) is a Japanese word meaning “precision,” “exquisite workmanship,” or “refined craftsmanship.”
It comes from the characters:

• 精 (sei) – fine, precise, refined

• 工 (ko) – craft, workmanship

Originally, Seiko’s watchmaking division was called Seikosha (精工舎), meaning “House of Precision.”
The name first appeared on a watch dial in 1924, shortened from Seikosha and keeping the core meaning; the company itself was renamed Hattori Seiko in 1983 and Seiko Corporation in 1990.

So the brand name literally ties directly to the idea of precision engineering—which is exactly what the company wanted to be known for in its watches.

🕰️The Seiko Actus Line: A Legacy of JDM Quality

The Actus line was a specialized mid-range series produced by Seiko from the late 1960s through the 1970s. While the standard “Seiko 5” was marketed globally as a rugged, affordable everyday watch, the Actus was primarily intended for the Japan Domestic Market (JDM), targeting young professionals who desired a blend of style and higher-end features.
The name “Actus” is derived from the Latin word for “action” or “motion,” reflecting the active lifestyle of the era’s youth. The line is defined by three distinct characteristics:

1. The “SS” Designation: The Actus versions built on the cal. 6106, this one among them, carry the SS (Second Setting) badge on the dial. This refers to the stop-seconds device, which halts the seconds hand when the crown is pulled out, allowing the watch to be set to the second. Most Seiko 5s of the period had no stop-seconds device at all, which is what the badge was there to mark.
2. Design Forward: Actus watches often experimented with bold case shapes, faceted crystals, and vibrant sunburst dials that pushed beyond the conservative styling of the standard Seiko 5.
3. The 5 Attributes: Despite the stylistic upgrades, the Actus remained a “Seiko 5” at its core, adhering to the five essential pillars: automatic winding, day/date display, water resistance, recessed crown at 4 o’clock, and a durable case/bracelet.

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Product Description
This Seiko 5 Actus SS was sold on the Japanese home market. Inside is the 23-jewel cal. 6106C, the variant of the caliber whose C suffix denotes the bilingual Kanji/English day wheel.
The “SS” (Second Setting) marking on the dial denotes the stop-seconds device: pulling the crown halts the seconds hand, so the watch can be set against a time signal to the second. The 37mm stainless steel case has a cushion profile with faceted flanks that run straight into the bracelet.
It comes on its original bracelet, the clasp signed SEIKO and ACTUS. The silver sunburst dial shifts from bright chrome to deep metallic grey as the angle changes.

• Condition: Fully serviced, movement regulated to within vintage tolerances. Original finish maintained.
• Movement: 23-Jewel 6106C Automatic (Hacking)
• Dimensions: 37mm diameter | 42mm lug-to-lug | 11mm thickness
• Market: Japan Domestic Market (JDM)

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Technical Specifications

• Caliber: Seiko 6106C (Automatic, Diashock shock protection)
• Jewel Count: 23 Jewels
• Vibrations Per Hour: 21,600 bph (3 Hz)
• Power Reserve: Approximately 45 hours
• Jewel Settings: Diafix oil-retaining cap jewels — what separates the 23-jewel 6106C from the 17-jewel version of the same caliber
• Calendar Mechanism: “Push-set” quickset. Pushing the crown in halfway changes the Date; pushing it deeper changes both Day and Date.
• Day Wheel: Dual-language (Kanji/English), indicative of its JDM (Japan Domestic Market) origin.
• Case Reference: 6106-8670 (cushion case with faceted flanks and an integrated-style bracelet transition)
• Case Back: Stamped SEIKO / WATER RESISTANT / 4N6198 / JAPAN A / 6106-8670, with the Suwa Seikosha whirlpool emblem; the 4N serial dates it to November 1974
• Case Material: Stainless steel, as stamped on the case back
• Crystal: Mineral Hardlex (proprietary Seiko hardened glass)
• Lug Width: 18mm

This watch has recently been serviced by a professional watchmaker and keeps good time.

Comes complete with original stainless steel bracelet included*.

(*)Note: Stock bracelets are often shortened by previous owners and may not fit you(see bracelet size in the product images). We match the strap to this watch’s lug width, so there is nothing for you to measure — just pick a padded leather strap for Seiko from the options at the top of the page.

Modes of payment:

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• bitcoin

We guarantee the item you receive looks and works exactly as advertised — or your money back.

Seiko Group Corporation (セイコーグループ株式会社, Seikō Gurūpu kabushiki gaisha), commonly known as Seiko, is a Japanese maker of watches, clocks, electronic devices, and semiconductors. Founded in 1881 by Kintarō Hattori in Tokyo, Seiko introduced the world’s first commercial quartz wristwatch in 1969.

Seiko is widely known for its wristwatches. Seiko is one of the few watch companies that is fully vertically integrated. Seiko is able to design and develop all the components of a watch, as well as assemble, adjust, inspect and ship them in-house. Seiko’s mechanical watches consist of approximately 200 parts, and the company has the technology and production facilities to design and manufacture all of these parts internally.

Seiko offers one of the widest ranges of watch technologies in the world—quartz, kinetic, solar, mechanical, and Spring Drive—spanning everything from affordable everyday pieces to six-figure haute horlogerie. Over the decades it has launched multiple global brands, including Lorus, Pulsar, and Alba, while elevating its prestige through innovations like Spring Drive, which helped push Seiko into higher-end territory. In 2017, Grand Seiko was spun off into its own standalone luxury brand, while Credor remains part of Seiko’s own lineup, sold primarily in Japan. Seiko’s own global lineup now includes Grand Seiko, King Seiko, Prospex, Astron, Presage, and Seiko 5 Sports.

Among Seiko’s key lines, Seiko 5 (born in 1963) is the gateway mechanical series known for durability and value; Lord Matic defined 1970s style with faceted crystals and colorful dials; Astron remains Seiko’s flagship GPS-solar tech line; Presage focuses on traditional mechanical craftsmanship with enamel and urushi dials; and Prospex delivers professional-grade dive, field, and pilot watches often embraced by enthusiasts. At the top end, Grand Seiko emphasizes precision, Zaratsu polished design, and movements like Spring Drive, while King Seiko—revived in the 2020s—brings back sharp, elegant 1960s styling with modern calibres.

Finally, Credor represents Seiko’s pinnacle of artisanal watchmaking, producing low-volume pieces in precious metals and showcasing Japanese decorative arts and haute complications from the Micro Artist Studio. Beyond watches, Seiko has also produced various electronic devices and, historically, jewelry and eyewear—though those divisions have since shifted to other companies.