Eight screws. That is the whole thing.
Everyone fixates on the octagonal bezel, and the bezel is the easy part. Anybody can cut an eight-sided ring. What separates a Royal Oak mod that looks like the real shape from one that looks like a costume is whether those eight exposed screws sit level, evenly spaced, and at the same depth all the way around. Get one of them a fraction proud and your eye catches it before your brain knows why.
So this is not a list of colours. It is what actually varies across the eight Seikoak builds we make, what each one costs at each size, and which of the three movements you end up living with.
What is in this guide
- What a Seikoak actually is
- The eight screws are the tell
- Three movements, not one
- All eight dials, compared
- 41mm or 39mm
- What is inside
- If the Royal Oak shape is not you
- Common questions
What a Seikoak actually is
"Seikoak" is not our brand name. It is what the modding community calls a Seiko mod built in the Royal Oak silhouette, and enough people type it into Google that it has become the working term for the shape.
A Seiko mod is a watch built around a genuine Seiko movement, with the case, dial, hands, bracelet and crystal specified rather than inherited. A Seikoak applies that to the integrated-bracelet sports watch that arrived in 1972 and rewrote what a steel watch could cost: octagonal bezel, eight exposed screws, a waffle-textured dial, and a bracelet that grows out of the case instead of being pinned to it.
It is a homage, not a copy. There is no other brand's name anywhere on it, and we tell you exactly which movement is inside each build. If that distinction matters to you, and it should, read this first.
The eight screws are the tell
Pick up a bad one and the screws are where it falls apart. Slightly different depths, rotated at random angles, or slots that were stamped rather than cut. On a shape this specific that reads as wrong immediately, even to someone who has never heard of the original.
The second tell is the bracelet join. On a cheap integrated-bracelet build you can see the exact point where the bracelet meets the case: a gap, a change in brush direction, an angle a degree or two off. On a good one the line runs unbroken from bezel to clasp and keeps tapering the whole way down.
That taper is also what stops a 41mm integrated watch feeling like a slab of steel strapped to you. It is the hardest thing to get right at this price, which is why bracelets are the part of the build we get asked about most.
Three movements, not one
This is the part most Royal Oak mod listings gloss over. The eight Seikoak builds do not share a single movement. They run three, and the one you pick changes what the watch does day to day.
Genuine Seiko NH35 automatic powers five of the eight: Black, Blue, Light Blue, Rose Gold and White. It winds itself as you wear it, it hand-winds if it has been sitting in a drawer, and it hacks when you pull the crown so you can set it to the second. It is the workhorse the entire modding world is built on, and it carries a date. How it compares to the alternatives.
Genuine Seiko NH70 automatic powers the Skeleton. Same self-winding principle, but open-worked, so you watch the gear train and balance wheel move through the dial, with an exhibition caseback at the rear so you can watch it from behind too. No date. It is the most mechanical-feeling watch in the range.
Genuine Seiko VK63 meca-quartz powers the two chronographs, Black and Panda. Meca-quartz is worth understanding rather than dismissing. The timekeeping is quartz, so it is accurate and you are not resetting it every week, but the chronograph itself is mechanical. You get the real pusher click, and the seconds hand snaps back to zero instead of sweeping lazily home. On a chronograph, that snap is most of the pleasure.
Neither automatic nor meca-quartz is better in the abstract. If you want to feel a mechanism doing work, take the NH35 or the NH70. If you want a chronograph you will actually use, and a watch that is still right when you pick it up in three weeks, take the VK63.
All eight dials, compared
Same octagonal bezel, same exposed screws, same sapphire crystal, same integrated 316L steel bracelet across all eight. The dial, the finish and the movement are the entire decision.
| Build | Dial | Movement | 41mm | 39mm |
|---|---|---|---|---|
| White | Silver-white waffle texture | Seiko NH35 automatic | A$349 | A$379 |
| Black | Black dial, steel bezel | Seiko NH35 automatic | A$349 | A$379 |
| Blue | Blue waffle texture | Seiko NH35 automatic | A$349 | A$379 |
| Light Blue | Pale blue on steel | Seiko NH35 automatic | A$349 | A$379 |
| Rose Gold | Black waffle, rose-gold case | Seiko NH35 automatic | A$349 | A$379 |
| Skeleton | Open-worked, exhibition back | Seiko NH70 automatic | A$349 | A$409 |
| Chrono Black | Black dial and registers | Seiko VK63 meca-quartz | A$349 | not offered |
| Chrono Panda | Silver dial, black registers | Seiko VK63 meca-quartz | A$349 | not offered |
Read them as behaviour rather than colour:
- White is the most versatile of the eight, and the one that works in an office without commentary.
- Blue is the colourway the shape is best known for. If you have a picture of this watch in your head, it is probably blue.
- Black is the sharpest contrast and the easiest to read at a glance.
- Light Blue is the contemporary one, and the people who want it are not shopping the others.
- Rose Gold is the dressy end of a sports-luxe line: warm case, black waffle dial.
- Skeleton is for people who want the mechanism to be the point.
- Chrono Panda is the loudest of the eight, and it does the work of a much more expensive watch across a table. More on why that two-colour layout works.
- Chrono Black is the same watch with the volume down.
41mm or 39mm
Six of the eight come both ways. The two chronographs are 41mm only.
An integrated-bracelet watch wears larger than its number, because there are no lugs. The case simply ends and the bracelet begins, so nothing overhangs the edge of the shape and nothing hides it either. In practice a 41mm Seikoak sits close to where a 42 or 43mm traditional watch would sit on your wrist.
The short version. If your wrist is around 17cm or above, take the 41mm, which is also the cheaper of the two at A$349. If you are under about 16.5cm, or you have worn a 40mm watch and found it slightly too much, the 39mm at A$379 is the one. The Skeleton in 39mm is A$409, because the NH70 costs more to build in the smaller case.
We size the bracelet to your wrist before it ships, rather than posting you a bag of loose links and a push pin.
What is inside
Named plainly, because the whole argument for buying one of these is that nothing is dressed up.
- Movement: genuine Seiko NH35 automatic, Seiko NH70 automatic, or Seiko VK63 meca-quartz chronograph, depending on the build above.
- Case: 316L stainless steel, 41mm or 39mm, integrated bracelet. Rose Gold is PVD-plated.
- Crystal: sapphire on every build. It resists scratches in a way ordinary glass does not, and the gap is wider than it sounds.
- Water resistance: 50m (5 ATM), which covers rain and hand washing. It is not a swimming watch and we are not going to imply it is. What that rating actually means.
- Warranty: 1 year, handled by us in Australia.
- Lead time: built to order in about 2 to 3 weeks, then shipped free within Australia.
Looking for a Seiko skeleton watch?
A lot of people land here after searching "seiko skeleton", so here is the direct answer. A skeleton watch has an open-worked dial that exposes the moving gear train and balance wheel. In our range that is the Seikoak Skeleton: a genuine Seiko NH70 automatic you can watch working from the front, with an exhibition caseback at the rear. A$349 in 41mm, A$409 in 39mm, and it lives in the Royal Oak collection with the other seven builds on this page.
If the Royal Oak shape is not you
The other integrated-bracelet family we build is the Nautilus, which runs a rounded octagon and a horizontally grooved dial instead of the sharp eight-screw architecture. Softer, and it starts lower at A$329. We compared the two shapes directly here.
If you want something that reads traditional rather than sporty, the Datejust family runs a conventional case and bracelet from A$289.
Made to be looked at twice.
Browse the whole Royal Oak range · Seiko Mod Watches, Explained by People Who Sell Them · See the White · See the Chrono Panda · Read the full buyer's guide
Common questions
What is a Seikoak?
A Seikoak is a Seiko mod built in the Royal Oak silhouette: an octagonal bezel with eight exposed screws, a waffle-textured dial, and an integrated steel bracelet, running a genuine Seiko movement. It is a homage to the shape, not a replica of any particular watch, and it carries no other brand's name.
How much is a Seikoak?
Ours are A$349 in 41mm across all eight builds. The 39mm case is A$379, except the Skeleton at A$409. The two chronographs are offered in 41mm only.
Is a Seikoak automatic?
Six of the eight are. Five run a genuine Seiko NH35 automatic and the Skeleton runs a Seiko NH70 automatic. The two chronographs run a Seiko VK63 meca-quartz, which keeps time by quartz but drives the chronograph mechanically.
Can you swim with a Seikoak?
No. These are rated 50m (5 ATM), which covers rain, hand washing and getting caught in the weather. It is not a swimming or diving watch. Choose a diver mod if you want water use.
Does a 41mm integrated-bracelet watch wear big?
Yes, larger than the number suggests, because there are no lugs to soften the transition. A 41mm Seikoak wears closer to a 42 or 43mm conventional watch. Wrists under about 16.5cm are usually happier in 39mm.
Sources
Primary references for the technical and regulatory claims above.
- Time Module (Seiko Instruments) NH-series product line-up - manufacturer specifications for the NH-series calibres.
- ISO 22810:2010, Horology - Water-resistant watches - what a water-resistance rating is actually tested against.