SKX013 GMT 38 Batman — Ultra Thin Watch Case

PRE-ORDER · Ships 21 October 2026. 30% off while the first production run is open — the price returns to full at launch. The GMT Bezel. Reborn Ultra Thin. Clicks Intact. The SKX013 GMT 38 Batman is a true bidirectional 24-hour GMT bezel on a 38mm case - black for the night hours and blue for the day - built on our SKX013 Diver 38 platform. Two timezones and dive-watch proportions, on a wrist size the travel-watch category mostly stopped serving. Making a dive bezel turn both ways is usually done the lazy way - bend the bezel click spring until it stops resisting in one direction. It works, and it ruins the feel. We were not willing to trade the click for the function, and we were not willing to delete the click spring and ship a bezel that spins like a bottle cap. So we re-engineered the bezel and the case together. There is no bezel click spring in this case. In its place, two spring-loaded pill detents are set into the case on opposite sides, buried beneath the bezel, indexing it from underneath. The result is a bidirectional 120-click bezel that still clicks - properly, evenly, both ways. A GMT bezel you can actually use to track a second timezone, with the tactile feedback of a dive bezel. As far as we know, nobody else has built one this way. It costs 0.40mm, and the reason is the movement. This case is built for the NH34, and the NH34 stands 7.99mm tall against 7.59mm for the three-hand NH calibres - exactly 0.40mm more. So the SKX013 Diver 38's 10.86mm becomes 11.26mm here, and every caseback carries the same 0.40mm forward. Nothing else moved: 38mm diameter, 40mm across the crown guards, 46mm lug-to-lug, 20mm lugs, 316L steel, crown at 3 o'clock, and the same SKX-style crowns and SKX013-spec chapter rings you already own. Bezel, insert and sapphire pre-fitted. Ready to assemble. The detent mechanism is set during assembly, not something you fit at a kitchen table - so the bezel, the black and blue ceramic insert and the sapphire crystal all ship pre-fitted and pre-aligned from our Singapore workshop. No crystal-pressing, no bezel fitting, no sticking and aligning the insert. For a GMT build, that is the hardest workshop time - done for you. Wears 38, looks bigger. Case diameter 38mm. With crown guards the case width reaches 40mm. Lug-to-lug 46mm, lug width 20mm. A traveller's proportions on a small-wrist canvas. See how we measured it against a 42.5mm SKX007 . Genuinely thin. 11.26mm with the Ultra Thin solid caseback - and every one of those millimeters is spoken for. The NH34 movement alone is 7.99mm. That leaves just a few millimeters for the crystal, walls, and hand clearance, on a movement that is already the tallest in the NH family. Tight engineering. Bidirectional. Still clicks. No bezel click spring. Two spring-loaded pill detents sunk into the case index the bezel from beneath - 120 clicks, both directions, with the tactile feel of a dive bezel. Our own engineering, and the reason this case exists. Three casebacks, cyclops fitted. Pick the Ultra Thin solid caseback for the headline thinness, the thicker solid caseback for full 200m water resistance, or the sapphire caseback to display the movement - and consider adding a decorated rotor for a fully customised view through the back. The cyclops crystal is fitted as standard on all three, magnifying the date window at 3 o'clock. Caseback Total Thickness Water Resistance Best for Ultra Thin Solid · HEADLINE BUILD 11.26mm 100m / 10 ATM Daily wear - the thinnest GMT profile Thick Solid 11.76mm 200m / 20 ATM Travellers who actually get it wet Sapphire 12.16mm 100m / 10 ATM Movement display - show off the rotor The Ultra Thin Solid caseback is the headline build - this is the case at its slimmest. The other two are for buyers prioritising water resistance or movement display, and add slight thickness in exchange. Each is exactly 0.40mm over the matching SKX013 Diver 38 caseback - the height the taller NH34 needs. Heads up — sold separately Crown. The crown shown in product photos is for visual reference only. Crowns must be selected above — choose from 5 SKX013-compatible options. Browse compatible crowns . Chapter ring. This case requires a SKX013-spec chapter ring to seat the dial correctly — without it, the dial sits too low and hands won't clear. The case fits both normal and ultra thin chapter rings; the choice depends on your dial, not the case. If your dial has applied (raised) indices, choose ultra thin for clearance. If flat-printed, either works. When in doubt, ultra thin is the safer default. Browse compatible chapter rings . For experienced modders only — TYPE M movements only This case is built for the NH34 and takes no other movement. It fits the TYPE M NH34 only - TYPE L will NOT fit. Due to tight clearance between hands and sapphire, this case is recommended only for professional watchmakers and experienced modders. Second-hand clearance: for optimal clearance the second hand must be under 12mm in length - or use a second-hand cap. Confirm before assembly. Dials and hands must be GMT. The case takes a 28.5mm GMT dial and a four-hand set including a GMT hand. A three-hand dial will leave the 24-hour hand with nothing to read against. Specs Build Guide What's Included How To Mod Dimensions Case Diameter 38mm Case Width (with crown guards) 40mm Case Thickness 11.26mm (Ultra Thin Solid) / 11.76mm (Thick Solid, 200m) / 12.16mm (Sapphire) Lug to Lug 46mm Lug Width 20mm Materials & Finish Quality Swiss Production Quality, ISO 9001 Certified Case Material 316L Stainless Steel Case Finishing Brushed (lug tops), Mirror polished (lug sides) Bezel Bidirectional rotating, 120-click, indexed by twin spring-loaded pill detents in the case - no bezel click spring (pre-fitted at workshop, exclusive to this case) Bezel Insert Black and blue 24-hour ceramic - black from 18 through 24 to 06, blue from 06 to 18 - with numerals every two hours and a reference triangle at 24 Crystal Flat Sapphire with clear AR coating, cyclops fitted as standard (pre-installed, exclusive to this case) Crown Screw down, SKX-style compatible, 3 o'clock Compatibility Movements TYPE M NH34 only (GMT with date) Dials 28.5mm GMT dials Chapter Rings SKX013-spec (required, sold separately) Hands NH34-compatible four-hand set including a GMT hand Crowns 7mm SKX-style Bracelets Lucius Atelier bracelets only (designed exclusively for our cases) Water Resistance Ultra Thin Solid Caseback 100m / 10 ATM Thick Solid Caseback 200m / 20 ATM Sapphire Caseback 100m / 10 ATM New to Seiko modding? Here's everything you'll need for a complete, functioning watch — in the order you'd actually assemble it. What's already in this purchase: The case body, bezel + ceramic insert (pre-fitted), and your chosen caseback + crystal. That's the foundation. Everything below is what you'll add to make a functioning, wrist-ready watch. The 5 parts you'll need for a complete watch: Chapter ring — required first. The chapter ring seats the dial at the correct height; without it, the dial sits too low and the hands won't clear. (SKX013-spec — sold on a separate page. See the "sold separately" panel above for normal vs ultra thin guidance.) Browse compatible chapter rings Crown — five SKX-style options. Pick a style that matches the watch's character. (Required to add to cart. Selected from the dropdown above on this page.) Browse compatible crowns Dial (28.5mm) — the face of the watch. The biggest aesthetic choice you'll make. Match it to your chosen movement. Hands — a four-hand set including a GMT hand - hour, minute, second, and the 24-hour hand that reads against the bezel. Most modders match lume colour across hands and dial markers (BGW9 white-blue, C3 green, etc.). Movement — NH34 only. This case is built around the NH34 - GMT with date, and the movement the bidirectional bezel exists to serve. No other calibre fits; the case height was drawn for the NH34's 7.99mm. Optional finishing touches: Bracelet or strap (20mm lug) — Lucius Atelier oyster, jubilee, president, GS, Seikonaut, Settimo, or more designs, plus custom shell cordovan / full-grain cowhide leather straps. Decorated rotor (only visible with sapphire caseback) — replace the stock NH movement rotor with our Côtes de Genève decorated rotor, viewable through the sapphire caseback. Recommended for experienced modders only — or tick Assemble Watch below and we'll handle it. Want it built for you? Tick the Assemble Watch (+SGD $89) option above on this page and we'll handle the full build in our Singapore workshop — case fitting, movement seating, crown alignment, caseback press, function check, and decorated rotor installation if you've added one. Heads up: assembled watches require 3–5 business days of workshop time before shipping. Once your parts arrive, see the How To Mod tab for assembly tutorials. 1x Watch Case Body (with pre-installed flat sapphire crystal, cyclops fitted as standard) 1x Bezel + Black And Blue 24-Hour Ceramic Insert (pre-fitted, pre-aligned) 1x NH Caseback (Ultra Thin Solid / Thick Solid / Sapphire, per selection) All photos of watches with modification parts are for illustration purposes only and are not included with the case purchase. A Complete Guide On How To Mod Your SEIKO Watch Dial And Hands (Photos & Video) Fitting dials with four dial legs Seiko Modding: The Complete Build Guide (2026)