NH35 : Le Mouvement au Cœur de nos Seiko Mods

NH35: The Movement at the Heart of Our Seiko Mods

If you've ever wondered what makes a Seiko Mod tick, the answer is almost always the same: the NH35A movement. This Japanese automatic caliber is the beating heart of the vast majority of our Seiko Prestige watches, and understanding why we trust it will help you better appreciate your watch—and choose it more wisely.

What is the NH35A movement?

The NH35A is an automatic mechanical movement manufactured by Seiko Instruments Inc. (SII), a Seiko subsidiary dedicated to producing watch movements. It is the direct evolution of the famous 7S26—the movement that made Seiko famous worldwide since the 1990s.

Concretely, "automatic" means that the movement winds itself thanks to the natural movements of your wrist. A rotor (a semi-circular part) pivots with every arm movement and winds the mainspring. The result: you never need a battery, and if you wear your watch regularly, it will stay perfectly on time.

Technical specifications of the NH35A

  • Type: Mechanical automatic (bidirectional winding by rotor)
  • Frequency: 21,600 vibrations per hour (6 beats per second)
  • Power Reserve: 41 hours without wearing the watch
  • Complications: Date (window at 3 o'clock or 6 o'clock depending on model), hour/minute/second hands
  • Jewels: 24 — jewels act as anti-friction bearings for moving parts
  • Accuracy: -10 / +30 seconds per day (automatic standard)
  • Manual winding: Yes, possible via the crown
  • Anti-magnetism: Standard (not high-performance anti-magnetic)
  • Transparent case back: Compatible — you can admire the movement through a sapphire case back

Why the NH35 and not another movement?

The world of automatic watches offers dozens of movements. Here's why the NH35A stands out as the obvious choice for Seiko Mods:

1. Proven reliability for decades

The NH35A is an evolution of the 7S26, used in millions of watches since 1996. Its design is mature, its weaknesses are known and corrected. It's a movement that runs for 20 years without revision if you maintain it minimally—a luxury that few entry-level Swiss Made movements can offer.

2. Universal service access

Any competent watchmaker can service an NH35A. Parts are available worldwide at reasonable prices. Unlike the proprietary movements of some brands, your Seiko Mod will never be "orphaned" if it needs maintenance in 10 years.

3. Unbeatable value for money

For what you pay, the NH35A offers robustness, accuracy, and longevity that few movements can match in this price range. Entry-level Swiss brands (Tissot, Hamilton) use ETAs whose cost often exceeds that of a complete Seiko Mod.

4. Transparent case back compatible

Our Seiko Mods Open Heart and some models with transparent case backs allow you to admire the NH35A in action. The rotor oscillates, the gears turn, the jewels sparkle in the light—a unique spectacle that quartz watches cannot offer.

NH35 vs other movements in our Seiko Mods

Depending on the models, our Seiko Mods are equipped with different movements:

  • NH35A → the vast majority of our catalog (Nautilus, Royal Oak, Datejust, Submariner, Santos...)
  • NH34 GMT → exclusively for our GMT Master II models. The NH34 adds a true GMT function with an independent hand adjustable hour by hour.
  • VK63 Hybrid Meca-Quartz → for our Seiko Mod Daytona and chronographs. This hybrid movement offers quartz precision with the instant responsiveness of pushers—purely mechanical chronographs at this price simply do not exist.

How to maintain your NH35A movement?

The good news: the NH35A requires very little maintenance.

  • Wear your watch regularly → 6 to 8 hours a day is enough to keep the movement wound
  • If you don't wear it → manually wind it via the crown before putting it back on your wrist (about 20 turns of the crown)
  • Full service → recommended every 5 to 7 years by a watchmaker (cleaning, lubrication, adjustment)
  • Avoid strong magnetic fields → loudspeakers, MRIs, strong magnets can affect accuracy
  • Water resistance → have the seals checked every 2 years if you regularly expose your watch to water

All our Seiko Mods are equipped with quality movements, checked before shipment, and covered by our 2-year warranty. Discover our complete collection — free delivery in France.

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