Explorer 36mm DLC Black — Ultra Thin Watch Case

Very. DLC is one of the hardest commercially available coatings on watch cases — harder than the steel underneath it. Under normal wear (belt buckles, desk edges, door frames, daily contact), it resists scratching far better than any PVD-coated mod case. Hard impacts can still mark the underlying steel, and like any coating it's not immune to deliberate abrasion — but for daily wear, it stays looking new for years longer than PVD.

No — the caseback is supplied in uncoated stainless steel. It sits against the wrist and isn't visible when the watch is worn, so it's left uncoated to keep the case priced as accessibly as possible. The case body, bezel and lugs all carry the full DLC black coating — every surface that's visible when the watch is on your wrist.

DLC (Diamond-Like Carbon) is a hard, amorphous carbon coating with properties similar to natural diamond. It's significantly harder and more scratch-resistant than PVD (Physical Vapor Deposition) — roughly 5× the hardness of 316L stainless steel. PVD coatings, by contrast, are softer and prone to wear through at high-contact points (lug edges, crown, bezel) over time. DLC stays put. It also doesn't fade in colour the way PVD can after years of UV exposure.

The solid caseback (9.96mm) is the headline build — this is the case at its thinnest, and the all-black stealth read on the wrist is at its purest. Choose sapphire (10.9mm) if you want to display the NH movement and rotor through the back. Both are rated 100m / 10 ATM, and both are supplied in uncoated steel.

The crown is selected on this page from {Coin Edge 6mm, Coin Edge 7mm, Knurled 6mm, Knurled 7mm} × {Sterile, Signed S}. For grip and ergonomics: knurled designs grip better than coin-edge, and 7mm crowns grip better than 6mm. Crown grip ranking, best to worst: Knurled 7mm > Coin Edge 7mm > Knurled 6mm > Coin Edge 6mm. Visually, 7mm crowns look slimmer than 6mm even at the same thickness — a Müller-Lyer-style optical effect from the lugs framing the crown.

DLC coating is a more demanding manufacturing process than PVD — it requires specialised vacuum chambers, higher temperatures, and more precise control of the carbon plasma deposition. The materials and equipment cost significantly more. We pass through some of that cost, but we keep the DLC case priced as accessibly as we can because we want the coating to be more common in modding, not less.

Type M and Type L are Seiko's two factory hand-fitting versions of the NH series. Type L sits higher than Type M — about 0.4mm taller from base to second-hand pinion. Because of the tight clearance between hands and sapphire in Ultra Thin Edition cases, only Type M will fit. Confirm your movement type before ordering.

No — and that's the whole point of us pre-installing the sapphire for you. The chapter ring sits on top of the dial inside the case, not under the crystal, so the crystal stays where it is throughout the build. (If you ever do need to remove the sapphire — for example, to replace it — that's a workshop job we handle for you, not an at-home step.)

The choice depends on your dial, not the case — both sizes fit every Ultra Thin Edition case. If your dial has applied (raised) indices, the ultra thin chapter ring is the better choice because its slimmer profile gives the indices clearance instead of resting on top of them. If your dial is flat-printed (no applied markers), either size works. When in doubt, the ultra thin chapter ring is the safer default because it works with both dial types.

A specific size and spec used by Seiko in the SKX013 (discontinued 2019). The LA smaller-case lineup all uses this same spec, which means dozens of chapter ring designs work across every smaller case in the catalogue.

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.

Yes — every Ultra Thin Edition case requires an SKX013-spec chapter ring, sold separately. The chapter ring seats the dial at the correct height; without it, the dial drops and the hands will not clear properly.