Seiko mod: our watches with a Seiko movement
A Seiko mod is a watch built around a Seiko automatic movement. Ours carry only the Modus Horlogerie name: 33 models online from €295, free shipping, 3-year warranty, or build your own in the configurator.
ATLAS Aqua Gold Automatic · Brown dial, rubber strap
Automatic · Brown dial, rubber strap
From €295.00
Build my own
Case, dial, bezel, hands, strap: pick every part with a live preview, add an engraving or your logo. From €349.
Open the configurator3-year warranty ·30-day returns ·French company, SIRET 989 849 849 00017
What a Seiko mod is
A Seiko mod combines three things: a mechanical movement made by Seiko Instruments, a case, dial, hands and strap chosen one by one, and a final regulation. The expression comes from modding, the practice of enthusiasts who swap the parts of a watch to make it their own. The movement is the common base; the parts give the style.
At Modus Horlogerie, the watch carries our name and our dial. Seiko makes the movement and nothing else: the watch is designed, sold and guaranteed by Modus. So we say a mod watch with a Seiko movement, never a Seiko watch.
Which Seiko movement for which watch
All of them are Seiko Instruments calibres made in Japan. The exact calibre is listed on every product page.
| Calibre | What it does | |
|---|---|---|
| Seiko NH35Automatic, date | 24 jewels, 21,600 beats per hour, 41 hours of power reserve, hand winding and hacking seconds.DEPTH, AXIS, ATLAS, PRISM, FIELD, NAUTA | DEPTH, AXIS, ATLAS, PRISM, FIELD, NAUTA |
| Seiko NH34Automatic GMT | The NH35 base with an independent 24-hour hand, to read a second time zone.MERIDIAN | MERIDIAN |
| Seiko NH38Automatic, no date | An NH35 without the date window, for a cleaner dial.Some PRISM dials | Some PRISM dials |
| Seiko NH70Automatic skeleton | An open dial that shows the gear train and the balance wheel.ORBIT skeleton | ORBIT skeleton |
| Seiko VK63Meca-quartz chronograph | Battery-powered (about 3 years): quartz accuracy, a chronograph hand that sweeps the dial, an instant reset. It is not automatic.INTERVAL, COSMOS | INTERVAL, COSMOS |
Seiko Instruments rates its automatics at −20 to +40 seconds per day. That is the range for the movement alone; a unit in good condition usually runs well inside it.
Compare the calibresA Seiko mod and an original Seiko: the difference
Next to an original Seiko watch, only the movement is the same. The case, dial, hands, strap, brand and warranty are Modus's: Seiko does not make, sell or guarantee our watches. A mod watch also never uses another brand's name or logo: every Modus carries only the Modus Horlogerie name, on the dial and on the caseback.
How to choose a Seiko mod
Two watches can share the same movement and have almost nothing else in common. Here is what to check before you buy.
- The crystal
- Sapphire crystal resists scratches far better than mineral glass. All our watches have one.
- The case
- 316L stainless steel, the reference grade in watchmaking. If a seller only writes “alloy” or “metal”, ask for the grade.
- Water resistance
- 5 ATM at Modus: splashes and rain, not swimming or diving. That is why we say “dive-style” for the watches with a rotating bezel.
- The dial
- A dial without another brand's name or logo. On a Modus, only the Modus Horlogerie name appears.
- The warranty
- 3 years at Modus, an identified after-sales service and a service recommended every five years.
- The price
- Catalogue watches start at €295; the configurator starts at €349, options extra.
Price, delivery, warranty and returns
A catalogue watch ships within 24 to 48 business hours. A watch built in the configurator is prepared to order: allow 9 to 11 days, delivery included.
Shipping is free worldwide, with no minimum order. Outside the European Union, customs duties or local taxes may be charged on delivery. Every watch carries a 3-year Modus Horlogerie warranty. You have 30 days after receipt to change your mind; return shipping is at your expense unless the watch is faulty or not as described.
Ten collections of Seiko mod watches
Frequently asked questions
What is a Seiko mod?
A mod watch (from “modding”) is an automatic watch built from parts chosen one by one: case, dial, hands, bezel and strap, around a proven movement. The idea comes from enthusiasts who customised their own watches; when the movement is a Seiko, they call it a “Seiko mod”. At Modus, every watch carries our own brand and our own dial.
Seikomod, Seiko mods: what are they?
The same thing, spelled differently: “seikomod” as one word, “Seiko mods” in the plural. Both mean a watch built around a Seiko automatic movement, with a case, dial, hands and strap chosen separately. At Modus Horlogerie, every watch carries our name and our dial; only the movement comes from Seiko Instruments.
Where can I buy a Seiko mod in Europe?
Right here: the watches on this page are sold online, ship within 24 to 48 business hours and travel with free tracked shipping. Modus Horlogerie is a French brand (INOVEA GROUP, Écully, near Lyon). Outside the European Union, customs duties or local taxes may be charged on delivery. You can also build your own in the configurator, from €349.
Is a Seiko mod legal? Is it a real Seiko?
It is not a Seiko watch. The movement is a genuine Seiko calibre, made by Seiko Instruments, which sells it to independent brands under the TMI name; the watch is designed, sold and guaranteed by Modus Horlogerie, under its own name only. In 2025 Seiko published a notice about modified watches: they are not supplied or checked by Seiko, and neither its warranty nor its after-sales service covers them. The 3-year warranty on a Modus is therefore ours. What a watch must never do is reproduce another brand's name or logo: a Modus carries only the Modus Horlogerie name.
What warranty does a Modus Seiko mod have?
Three years against manufacturing defects, movement and 5 ATM water resistance included. It is Modus Horlogerie's warranty, not Seiko's: if something goes wrong, our after-sales service takes the watch in. Tracked shipping is free everywhere, with no minimum order. You have 30 days to change your mind; return shipping is at your expense unless the watch is faulty.
Which Seiko movement powers a Modus watch?
A Seiko automatic movement, made in Japan by Seiko Instruments: the Seiko NH35 calibre in most models, the Seiko NH34 in the GMTs, the Seiko NH70 in the skeletons and the Seiko VK63 in the chronographs. The watches are designed and sold by Modus Horlogerie.
Why the Seiko NH35 movement?
The NH35 is a 24-jewel automatic calibre with a date and hacking seconds. It's known for its robustness and it's easy to service: any watchmaker can work on it.
Does a mod watch carry another brand's name?
No. A Modus mod watch carries only the Modus Horlogerie name. It can take inspiration from the great watchmaking classics (dive-style, GMT, chronograph), but it never passes itself off as another watch or uses another brand's logo.
Can I build my own mod watch?
Yes. The Modus configurator lets you choose the case, dial, bezel, hands and strap, and add an engraving or your logo, with a live preview. A custom watch costs €349, plus any options you pick.
Is a Seiko mod reliable?
The movement is: the NH35 is mass-produced by Seiko Instruments, well documented, and any watchmaker can service it. The rest depends on the watch: 316L steel case, sapphire crystal, a well-made crown and gaskets, regulation and a warranty. Every Modus watch is covered for 3 years.
What is the difference between the NH35 and the VK63?
The NH35 is automatic: it winds itself with the movement of your wrist and has no battery. The VK63 is a meca-quartz: it runs on a battery (about 3 years) and drives a chronograph, with a seconds hand that sweeps the dial and an instant reset. It is more accurate than an automatic, but it is not automatic. Our INTERVAL and COSMOS watches use the VK63.
How long until I receive my watch?
A catalogue watch ships within 24 to 48 business hours. A watch built in the configurator is prepared to order: allow 9 to 11 days, delivery included.
How do I look after a Seiko mod?
Wear it, or give the crown 20 to 30 turns if it has stopped. Do not set the date between 9 pm and 3 am. Avoid hot water and showers: water resistance is 5 ATM. Plan a service every five years, by a watchmaker or by our after-sales team.
