Swatch · Sistem 51

Strap for Sistem Arrow

Takes 20 mm straps. Verified lug width, the straps that fit this model, and answers to the most common questions.

Lug width20 mm
Case diameter42 mm
ReferenceYIS403
FamilySistem 51
MovementSwatch caliber Sistem51 date
Year2016
CaseStainless Steel

Spring bar

Swiss Standard universal spring bars

The right category for this model · 316L steel, all lug widths 13–26 mm

Straps for the Sistem 51 YIS403

Selected for the 20 mm lug width · workshop selection

All 20 mm straps →

The Sistem 51 YIS403, seen from the bench

The Sistem 51 was introduced in 2013 as the first fully machine-assembled automatic mechanical movement. It uses the Sistem51 caliber with 51 components, 19 jewels, and date indication. The case is made of plastic material with a sealed, non-repairable movement.

Frequently asked questions

What is the lug width of the Swatch Sistem 51 YIS403?

The Swatch Sistem 51 YIS403 is fitted with a standard 20mm lug width. This measurement is compatible with any 20mm artisanal strap. To verify the measurement, measure the distance between the two lateral lugs where the strap attaches: if the measurement corresponds to 20mm, the strap will attach correctly.

What is the best strap for the Swatch Sistem 51 YIS403?

The choice depends on intended use and aesthetic preference. An alligator or vegetable-tanned calf leather strap enhances the visible movement through the exhibition caseback, creating a dialogue between contemporary craftsmanship and Swiss precision. A 4-rings NATO fabric strap embraces the model's sporting heritage, whilst structured rubber is ideal for those prioritising durability and everyday maintenance ease.

How do you change the strap on a Swatch Sistem 51 YIS403?

The Swatch Sistem 51 YIS403 employs a standard lug system without spring bars. To change the strap, gently remove the previous strap from the lugs by exerting light outward pressure. Insert the new strap into the lugs, ensuring both lateral spallettes seat correctly. If the lugs feel tight, you may briefly warm the new strap's ends in tepid water to soften the material.

Which aftermarket straps are compatible with the Swatch Sistem 51 YIS403?

Any strap with a 20mm lug width is compatible with the YIS403, provided the ends seat into the case lugs without forcing. Milano Straps curates a selection of artisanal straps in leather (alligator, calf, cordovan), NATO and technical rubber, all available in 20mm and tested for compatibility with the Sistem 51.

How long does a leather strap last on a daily-worn Swatch Sistem 51?

Durability depends on leather quality and usage pattern. A vegetable-tanned calf or alligator strap typically endures 18–36 months with daily wear, developing increasingly rich patina over time. Longevity increases if you protect the strap from prolonged exposure to perspiration, rain and direct sunlight. Straps crafted from artisanal-quality leather can be regenerated through polishing and oiling, extending operational life by several years.

The next step

The right strap isn't chosen. It is built, together.

From the atelier appointment to delivery, every step is made for those who know that things done well take time. Rare leathers, one piece at a time, eighteen months of warranty.

Request an appointment →

Casati Milano · Via XX Settembre 15, Milan · by appointment only