Technical Archive

Swatch
Sistem 51 SUTS402— lug 20mm

Swatch Sistem 51 SUTS402: 20mm strap. Alligator, box calf, shell cordovan and rubber, cut and stitched in Milano. Choose your leather.

Sistem Class

Artisanal Note

"This model requires a precise 20mm lug width to preserve the original sartorial balance."

Technical Specifications

Swatch SUTS402
Lug Width
20 mm

The essential strap measurement.

Browse 20mm straps →
Reference

SUTS402

Movement

Swatch caliber Sistem51 Date

The Heritage

The Sistem 51 was launched by Swatch in 2013 as the first fully machine-assembled automatic mechanical movement. It houses the Sistem51 caliber with 51 components, a power reserve of 90 hours, and a date display. The case features a completely welded construction with no possibility of opening for maintenance.

FAQ

What is the lug width of the Swatch Sistem 51 SUTS402?

The lug width of the Swatch Sistem 51 SUTS402 is 20 millimetres. This measurement, taken between the two attachment points on the case, is the dimensional standard that characterises this model and enables broad compatibility with aftermarket artisanal straps. To verify the lug width of your watch, position a digital calliper on the inside surface of the case, measuring the distance between the two extremes of the lug.

Which strap is most suitable for the Swatch Sistem 51 SUTS402?

For the Swatch Sistem 51 SUTS402, we recommend straps in vegetable-tanned leather with natural tanning, which create an elegant aesthetic contrast with the transparent case, or robust textile NATO straps for those who prioritise versatility and durability. Alligator materials offer structural solidity and visible texture, whilst vulcanised rubber ensures waterproofing and performance in sporting environments. Your choice depends on primary usage: everyday elegance, casual versatility, or outdoor activities.

How do you change the strap on the Swatch Sistem 51 SUTS402?

The strap on the SUTS402 is replaced by removing the spring pins (also called lugs) that connect the strap to the case lugs. Use a dedicated extraction tool, such as a strap removal device or a small metal bar. Gently remove the lateral pins, extract the worn strap, and insert the new strap by aligning the holes with the case lugs. Reinsert the pins with uniform pressure until fully secured. The operation requires only a few minutes and no technical expertise.

Is the Swatch Sistem 51 SUTS402 compatible with aftermarket straps?

Yes, the SUTS402 is fully compatible with aftermarket straps of 20mm lug width. This dimensional standardisation is one of the Sistem51's constructive advantages: it facilitates personalisation without requiring case modifications. The artisanal market offers hundreds of options in leather, rubber, textile and synthetic materials, all equipped with attachments compatible with your watch.

What is the lifespan of a leather strap on the Swatch Sistem 51 SUTS402?

The lifespan of a leather strap on the SUTS402 depends on the intensity of use, climatic conditions and construction quality. A vegetable-tanned leather strap of artisanal quality, with natural tanning, has an average life of 3-5 years under daily use conditions. The leather naturally softens, develops a characteristic patina, and eventually requires replacement when it loses elasticity. Vulcanised rubber straps last longer—6-8 years—due to their resistance to UV rays and humidity cycles. Regular maintenance (gentle cleaning, occasional conditioning) significantly extends longevity.