Will an NH35 dial fit in any case in this collection?

Yes. Every case in the Ultra Thin Edition is built around the standard 28.5mm dial size used across the NH35 / NH36 / NH38 family. If you have a dial that fits a Seiko SKX or any Seiko 5 NH-movement build, it will fit here. NH34 GMT dials are the exception — they need a wider 2.70mm centre hole.

Can I swap parts between cases in this line?

Yes — that's the point of the Ultra Thin Edition architecture. Chapter ring, dial dimensions, and hand post heights are consistent across the line. Dials, hands, and the chapter ring from any Ultra Thin Edition case work in any other. Movements (NH34/35/36/38) swap freely between cases that support them.

Do these cases come fully assembled, or do I build them?

These are case bodies sold for modding. They ship with the case, caseback, bezel (where applicable), sapphire crystal, and crown (where applicable). You supply the dial, hands, chapter ring, and movement. If you've never built a Seiko mod before, our full guide walks through the assembly: Seiko Modding: The Complete Build Guide

What wrist size do these fit?

The Ultra Thin Edition line is designed for the full wrist-size spectrum, with sweet spots based on case diameter: a 6.0–6.5 inch wrist suits 33–36mm cases; a 6.5–7.0 inch wrist suits 36–38mm cases; a 7.0–7.5 inch wrist still wears 36–38mm beautifully, with larger optional; and a 7.5 inch and larger wrist can take larger cases, though smaller cases still wear well.

Will SKX007 dials fit?

Any 28.5mm dial will fit. Stock SKX007 dials may seat differently because the original SKX007 has a 4 o'clock crown position with offset dial feet, while Ultra Thin Edition cases are designed for 3 o'clock dial feet.

What's the lug width? Can I use any 20mm strap?

Straps and NATOs are universal — any 20mm strap fits these cases, since the lug width is a standard 20mm. Bracelets are not: our bracelets use solid end-links shaped to the Lucius Atelier case profiles, so a generic 20mm bracelet or an OEM Seiko bracelet won't seat correctly. For a bracelet, pick one from our bracelet collection — it's built to fit these cases.

Is the crystal included?

Yes. Every Ultra Thin Edition case ships with an AR-coated sapphire crystal, pre-installed and aligned at our workshop. No separate purchase or installation required.

Can I change crown style after purchase?

For most cases in the line, yes — you can change crown style at any time to refresh the look of your build. Two exceptions to know up front: the Bauhaus 33mm ships with a fixed crown that can't be swapped, and the titanium cases can take a different crown, but our replacement crowns are made in 316L stainless steel — we don't currently offer titanium crown designs. Every other case takes a crown change freely.

Ultra Thin Edition Cases

PRE-ORDER · Three new SKX013 cases. Diver 38 Origin, GMT 38 Pepsi and GMT 38 Batman — ships 21 October 2026. 30% off while the first production run is open. Already in the price, no code needed.

Compact watches, properly engineered. The Ultra Thin Edition is our in-house case architecture — built around a 28.5mm chapter ring, 7.59mm NH caliber, and a total height that starts at 9.93mm. The line now runs 33mm to 39mm: small wrists get a proper modern silhouette instead of a chunky NH-stock compromise, and larger wrists get real presence without the bulk.

Every case in this line shares the same DNA — slim profile, 20mm lug width, and tight tolerances against our dials, hands, and bezels. Mix and match across the lineup with confidence: a Bauhaus 33 dial drops cleanly into a Pilot 34. An Explorer hand set fits the 1908. The architecture is the constant.

Which case is right for you?

Wrist under 6.5 inches? Bauhaus 33 or Pilot 34.
Want a daily workhorse? Explorer 36 — stainless, DLC black, or titanium.
Dressing up? 1908 36 (steel or yellow gold), GS 39, or Bauhaus 33.
Want the biggest slim case? GS 39 — the largest in the line.
Going GMT? Pilot 34, 1908 36, 62GS 36, and GS 39 are NH34-ready out of the box. Want a rotating 24-hour GMT bezel as well? SKX013 GMT 38 Pepsi or Batman — built for the NH34 only.
Going diving? SKX013 Diver 38 in Black, Green, or the new Origin — the SKX013's own minute-dot bezel, in ceramic. Up to 200m.
Want integrated bracelet luxury? Seiko-Dweller 36 — titanium, modern proportions.
Want sports luxury? Seikonaut 38 — premium proportions on standard 20mm lugs.

The lineup at a glance

Case	Style	Thickness	Material	Water resistance
Bauhaus 33mm	Minimalist dress	9.93mm	Steel	100m
Pilot 34mm · GMT-READY	Flieger / cockpit	10.96mm	Steel	100m
Explorer 36mm	Sport-casual workhorse	9.96mm	Steel / DLC / G4Ti	100m
1908 36mm · GMT-READY	Semi-fluted dress	10.75mm	Steel / Yellow Gold	100m
62GS 36mm · GMT-READY	Bezel-less, crown at 4	11.3mm	Steel	100m
Seiko-Dweller 36mm	Integrated sports titanium	10mm	G4Ti	100m
Seikonaut 38mm	Sports luxury	10mm	Steel / G4Ti	100m
SKX013 Diver 38mm	Professional diver — Black / Green / Origin	10.86mm	Steel	Up to 200m^¹
SKX013 GMT 38mm · NH34 ONLY · PRE-ORDER	Bidirectional 24-hour GMT diver — Pepsi / Batman	11.26mm	Steel	Up to 200m^¹
GS 39mm · GMT-READY	Faceted dress, largest	10.95mm	Steel	100m

GMT-Ready cases accept the Seiko NH34 GMT movement. NH34 Only cases are built around it and take no other calibre.
^¹ The SKX013 Diver 38 and GMT 38 reach 200m with the Thick Solid caseback option; the standard Ultra Thin caseback is rated to 100m. See the product page for the full caseback comparison. Water resistance ratings apply to the bare case as manufactured — final water resistance of an assembled watch depends on crown, gasket, and caseback installation by the modder.

Materials, movements, and crowns

Materials. 316L stainless steel and Grade 4 titanium are the two structural materials across the line. DLC (Diamond-Like Carbon) is available as a finish on the Explorer 36, applied over a 316L steel base.

Movements. Every case in the line except the SKX013 GMT 38 is compatible with NH35, NH36, and NH38 movements out of the box. GMT-Ready cases — Pilot 34, 1908 36, 62GS 36, and GS 39 — also accept the Seiko NH34 GMT movement. The SKX013 GMT 38 — Pepsi and Batman — is built around the NH34 and takes no other movement; its bidirectional 24-hour bezel exists to serve it. Note that NH34 requires a GMT-compatible dial with a 2.88mm centre hole; standard NH35 dials will not fit.

Crowns. Coin Edge, Knurled, Onion, Diamond, and 1908 crown styles are customer-selected. Crown choice is independent of case — pick the silhouette you want.

This is the case architecture we wished existed when we started modding in 2018. So we built it.