The NH35 is the most common movement in Seiko modding, and compatible parts are available from dozens of suppliers. But compatible doesn't always mean identical. Fitment depends on specific dimensions for each part category. Before ordering, check your exact combination in the Assemble Watches builder.
NH35 Movement Specs (Fitment Reference)
| Spec | Value |
|---|---|
| Outside diameter | 27.40 mm |
| Casing diameter | 29.36 mm with dial spacer |
| Movement height | 5.32 mm |
| Common dial size | 28.5 mm |
| Stem position | 3 o'clock |
| Date complication | Yes, date only |
| Dial feet standard | Seiko standard (NH35 / SKX spec) |
Compatible Cases
The NH35's published outside diameter is 27.40mm, or 29.36mm with its dial holding spacer. That footprint fits the vast majority of aftermarket mod cases on the market. The movement became the natural replacement for the 7s26 in the original SKX007, so any case built around that platform will usually accept it without modification.
The most common case format is an SKX-style case: approximately 44–45mm case diameter, 22mm lug width, and enough internal depth to accommodate the 5.32mm movement plus dial and crystal. Most dedicated mod case suppliers build to this spec, and it covers the widest range of compatible dials and bracelets.
If you're using a slimmer or smaller case, verify the internal depth before ordering the movement. The total stack, including the 5.32mm movement height, dial thickness, hand stack, and crystal, needs to clear the caseback without pressing against the crystal. Use the Assemble Watches builder to check a specific case against your chosen movement and dial.
Compatible Dials
NH35-compatible dials use Seiko-standard dial feet: two small metal tabs on the underside of the dial, spaced to fit the NH35's dial feet recesses. Most aftermarket dials sold for Seiko mod builds use this standard, and any listing that specifies NH35, NH36, or SKX compatibility will have the correct feet.
Dial diameter is typically 28–28.5mm, sized to sit inside the case over the movement without touching the case walls. If a dial is listed as 28.5mm and your case is SKX-spec, it will fit.
The date aperture is the cut-out in the dial for the date wheel. NH35 dials have an aperture sized for the NH35's single date wheel at 3 o'clock. NH36 dials have a different day-date aperture. The two are not interchangeable unless the dial is explicitly sold for both movements. Always confirm which movement your dial is cut for before ordering.
Compatible Hands
Hand compatibility is determined by tube diameter: the hollow shaft at the base of each hand that presses onto the movement's pinions. For the NH35, standard Seiko NH hand sizes are roughly 1.50mm for the hour hand, 0.90mm for the minute hand, and 0.20mm for the seconds hand. Any hand set listed as NH35 or SKX-compatible should use these sizes.
That said, tube sizing across different manufacturers can vary slightly in tolerance. If you're sourcing hands from a supplier who doesn't explicitly list NH35 compatibility, check their spec sheet before ordering. A hand with a tube that's too loose will wobble or fall off; one that's too tight risks damaging the cannon pinion when pressed on.
Compatible Crystals
Crystal sizing is determined by the case, not the movement. For SKX-style mod cases, crystals typically run 29.5mm to 30.5mm in diameter. Check your case spec for the exact size before ordering. Getting this wrong by even 0.5mm means the crystal either won't seat or won't hold.
Flat sapphire crystals are the standard choice for a clean, modern look. Domed crystals add a vintage character and are popular on dress and vintage-inspired builds. AR (anti-reflective) coatings reduce glare and are worth considering if your build will be worn in bright conditions.
Fitting method varies: tension-ring crystals press into a retaining ring that snaps into the case; adhesive crystals use a thin layer of watch crystal cement. Tension-ring fitting is more common in mod cases and easier to do without specialist tools.
Check Your Full Build Compatibility
The fastest way to verify that your chosen movement, case, dial, hands, and crystal all work together is to run them through the Assemble Watches builder. Select each part and the builder flags compatibility issues automatically, including dial aperture mismatches, case clearance, and hand sizing, before you spend anything.
Check compatibility in the builder →Frequently Asked Questions
Will any NH35 movement fit a SKX007-style case?
Usually yes. The NH35 shares the case footprint that aftermarket SKX-style cases are built around, so most dedicated mod cases accept it without modification. Still check the case listing before ordering, especially on slim or unusual cases.
How do I know if a dial fits an NH35?
Check that the dial specifies NH35 or SKX compatibility. This indicates the dial feet are cut to Seiko standard spacing and the date aperture (if present) is sized for the NH35's date wheel at 3 o'clock. Most aftermarket dial listings make this explicit.
What hand size do I need for an NH35?
The NH35 uses standard Seiko NH hand sizing: roughly 1.50mm for the hour hand, 0.90mm for the minute hand, and 0.20mm for the seconds hand. Any hand set listed as NH35 or SKX compatible should use these sizes, but verify the vendor specs before ordering.
Where can I check NH35 part compatibility online?
The Assemble Watches builder lets you select an NH35 movement and filter compatible cases, dials, hands, and crystals. It flags incompatible combinations before you buy anything.