Imagen: Swatch, web oficial
The storyWhy this reference matters
The Sistem51 arrived in 2013 and it was a genuine event, not a press release: a Swiss mechanical movement assembled entirely by machine, with nothing touched by hand anywhere on the line. Fifty-one parts, most of them held by one long central screw, nearly the whole assembly made in ARCAP — a copper, nickel and zinc alloy that neither picks up magnetism nor shifts with temperature — and ninety hours of power reserve. That first Sistem51 came in a plastic case with the back welded shut. Break it and you threw it away.
In 2016 came the twist a lot of us had been waiting for: the Sistem51 Irony. Same machine, but a brushed steel case and dials with metallic finishes instead of the plastic version's poster colours, at around thirty per cent more than the original. Seven models launched, six men's and one women's. The change that mattered was invisible: the Irony's plastic case back does come off, so the movement gets replaced rather than the whole watch binned.
The Sistem Arrow is the one in that series that decided to be serious. It borrows the German Type B Flieger dial layout — big minutes on the outer ring, small hours inside, triangle at twelve — on a matte black dial, in a brushed steel case with a toothed bezel set with black lacquer panels. A nod to Luftwaffe navigation watches from the least solemn brand on earth, and it works precisely because of that.
SpecificationsThe numbers, in one table
| Brand | Swatch |
|---|---|
| Family | Sistem51 Irony |
| Reference | YIS403 |
| Years made | desde 2016 |
| Calibre | Swatch Sistem51 |
| Movement | Automatico |
| Frequency | 21.600 alt/h (3 Hz) |
| Power reserve | 90 horas |
| Jewels | 19 |
| Complications | Fecha |
| Diameter | 42 mm |
| Thickness | 13.8 mm |
| Lug to lug | 50.6 mm |
| Case | Acero inoxidable satinado |
| Crystal | Plástico delante y en el fondo |
| Water resistance | 3 bar (30 m) |
IdentificationHow to tell it apart
The reference is a small mess. Swatch's own catalogue lists it as YIS403, but shops and databases also carry it as YIS403G, and the brand's own site search returns nothing for the G variant. It's the same Sistem Arrow: steel case, black Type B Flieger dial, black rubber strap, date at three under the word AUTOMATIC.
The dimensions and the materials set it apart from any other Swatch: 42 mm across, 13.8 mm thick, 50.6 mm lug to lug. Both crystals, front and back, are plastic rather than sapphire. And the lugs use Swatch's proprietary three-tab system, so no standard strap on the market will fit. It's a Swatch strap or nothing.
Through the back you can see the Sistem51's printed mainplate with its chequerboard decoration, and here's the nice detail: every Irony carries the same movement, but the printed decoration changes with the model, either a cube motif or a spiral. You can also make out the single central screw holding the whole thing together, which is the calibre's technical signature and looks like nothing else.
CollectingWhat collectors check
The movement isn't repaired, it's replaced. The bridges are permanently fixed, so a Sistem51 that won't start is not a restoration project — it's a complete calibre swap. Before buying, let it run for a few hours and check that the rotor winds without noise and that the date changes over. The good news is that on the Irony the case back comes off, which was not true of the original plastic Sistem51.
The plastic crystals scratch, but they also polish out, and that's an advantage over sapphire: a Sistem Arrow with a clean dial and a scuffed crystal can be brought back in an afternoon. The brushed steel case is another matter. A bad polish wipes out the directional grain on the toothed bezel and it never comes back. Hold the case up to the light and look for patches where the grain changes direction.
The 3 bar of water resistance means exactly that: rain and little else, no swimming. As for availability, the Irony series has come in and out of the catalogue over the years, so unworn examples still turn up on the market — with the original rubber strap fitted, which, thanks to that Swatch lug system, isn't easy to swap for just anything.
Common questionsWhat people ask us about this reference
How many parts does the Swatch Sistem51 have?
Fifty-one, hence the name. Most of them are held by a single long central screw, and the whole thing is assembled by machine with no manual intervention. It gives ninety hours of power reserve at 3 Hz, with 19 jewels.
Can a Swatch Sistem51 be repaired?
The movement itself, no: the bridges are permanently fixed and it doesn't come apart. On the steel Irony version, though, the plastic case back can be removed, so the calibre is replaced whole instead of throwing the watch away.
How much power reserve does the Sistem51 have?
Around ninety hours, close to four days. That's a striking figure at the price and one of the reasons the calibre caused such a stir when it launched in 2013.
Can I fit a different strap to the Swatch Sistem Arrow?
Only Swatch straps. The case uses the brand's proprietary system with three-tab lugs, so standard 20 or 22 mm straps won't fit. The upside is that official replacements are cheap.
Keep readingWhere to go from here
Close relativesThe ones it gets confused with
See Swatch Sistem51 Irony at auction now → What is up for sale on Catawiki today. Read the page above before you bid: half the mistakes come from not checking the reference.Confidence: media — this page was checked against the sources below. If a detail looks wrong to you, write to us and we will fix it.