Swatch · Sistem 51

Strap for Sistem Grid

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
ReferenceSUTN401
FamilySistem 51
MovementSwatch caliber Sistem51 date
Year2016
CasePlastic

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 SUTN401

Selected for the 20 mm lug width · workshop selection

All 20 mm straps →

The Sistem 51 SUTN401, seen from the bench

The Sistem 51 was introduced by Swatch in 2013 as the first automatic mechanical movement completely assembled by machines. The Sistem51 caliber is composed of 51 components with a date function and a 90-hour power reserve. The case features standard Swatch dimensions with a fully welded construction without the possibility of opening for maintenance.

Frequently asked questions

What is the lug width of the Swatch Sistem 51 SUTN401?

The lug width of the SUTN401 is 20 millimetres. This dimension represents the internal space between the two lugs of the case, measured from edge to edge. It is compatible with any aftermarket strap fitted with standard 20-millimetre attachments.

What is the best strap for the Swatch Sistem 51 SUTN401?

The ideal strap depends on usage: alligator with vegetable tanning for formal settings, NATO or technical rubber for sport and daily wear. We recommend black or dark brown alligator for contrast with the luminous case, or burgundy red shell cordovan for aesthetic sophistication.

How do you change the strap on the Swatch Sistem 51 SUTN401?

The SUTN401 features non-soldered lugs with standard spring bar attachments. Using a spring bar removal tool, press downward on the internal spring, extract the spring bar, remove the old strap and insert the new one by aligning it to the recesses. Reposition the spring bar and verify the locking mechanism.

Which aftermarket strap is compatible with the SUTN401?

Any strap with a 20-millimetre lug width is compatible. Avoid straps with deployante clasps thicker than 4 millimetres that could create tension on the plastic lugs. We recommend straps specifically tested for lightweight sport watches.

How long does a leather strap last on the SUTN401?

A quality leather strap (alligator, calf, shell cordovan) lasts 2–4 years with daily use and regular maintenance (drying, conditioning every 6 months). Longevity depends on environmental humidity, frequency of use and care. NATO and rubber straps last 5–8 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.

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