Swatch · Sistem 51

Strap for Sistem White

Takes 16 mm straps. Verified lug width, the straps that fit this model, and answers to the most common questions.

Lug width16 mm
Case diameter42 mm
ReferenceSUTW400
FamilySistem 51
MovementSwatch caliber Sistem51 date
Year2013
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 SUTW400

Selected for the 16 mm lug width · workshop selection

All 16 mm straps →

The Sistem 51 SUTW400, seen from the bench

The Swatch Sistem White SUTW400 features the proprietary Sistem51 automatic movement with 51 components, beating at 4 hertz and offering a 40-hour power reserve. The 42mm high-density plastic case is paired with mineral glass and an integrated bracelet, with a 16mm lug width. Launched in 2013 for Swatch's 50th anniversary, this sports watch represents accessible Swiss mechanical engineering with a fixed bezel and transparent caseback revealing the red rotor and automatic winding mechanism.

Frequently asked questions

What is the lug width of the Swatch Sistem 51 SUTW400?

The Swatch Sistem 51 SUTW400 features a lug width of 16 millimetres. This width is standard across the Sistem51 sports family and is readily compatible with a wide range of aftermarket straps in leather, NATO, and rubber.

What is the best strap for the Swatch Sistem 51 SUTW400?

The choice depends on your intended use: for a classic-elegant aesthetic, we recommend a vegetable-tanned leather strap in cognac brown; for a minimalist contemporary look, black or slate grey; for intensive sports use, a rubber strap with anti-slip texture. Calf leather offers the ideal balance between elegance and daily robustness.

How do you change the strap on the Swatch Sistem 51 SUTW400?

Strap replacement is performed via the spring bars on the case lugs. Equip yourself with a dedicated spring bar tool, gently disengage both spring bars by pressing downwards, extract the original strap, and insert the new one, ensuring the spring bars click into the anchor holes of the new strap. Seeking assistance from a specialist atelier is always advised if unfamiliar with the procedure.

Is an aftermarket strap compatible with the Swatch Sistem 51 SUTW400?

Yes, provided the strap features a 16-millimetre lug width. Any 16mm strap crafted by specialised artisans (leather, NATO, rubber) is entirely compatible with the SUTW400's spring bar attachments. We always recommend verifying the technical specifications with the manufacturer prior to purchase.

How long does a leather strap last on the Swatch Sistem 51 SUTW400?

Durability depends on frequency of use and material quality. A premium-quality leather strap (calf leather, vegetable-tanned) typically lasts 2–4 years under moderate daily wear. Continuous exposure to humidity, direct sunlight, and perspiration can reduce longevity. Regular maintenance (cleaning, drying, conditioning) significantly extends the strap's lifespan.

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