Nomos Glashütte · Tangomat

Strap for Tangomat GMT +

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

Lug width20 mm
Case diameter40 mm
Reference637
FamilyTangomat
MovementNomos Glashütte caliber Xi Hours, Minutes, Small Seconds, World Time
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 Tangomat 637

Selected for the 20 mm lug width · workshop selection

All 20 mm straps →

The Tangomat 637, seen from the bench

The Nomos Glashütte Tangomat 637 embodies Glashütte's philosophy of German watchmaking excellence since the 1940s. This 40mm stainless steel case model features a clean dial and the proprietary Nomos Glashütte Xi automatic caliber with 21,600 vph, certified to ±15 seconds per day. World Time function, 20mm lug width, and three-body case design reflect Bauhaus minimalism applied to everyday mechanical watchmaking.

Frequently asked questions

What is the lug width of the Nomos Glashütte Tangomat 637?

The lug width is 20mm. This dimension is critical for the proportionality of the 40mm case and conforms to the German standard for watches of this class. Always verify with a digital calliper the distance between the lugs before purchasing an aftermarket strap, as even 1mm of variation creates incompatibility.

What is the best strap for the Tangomat 637?

There is no absolute 'best'—it depends on intended use. For formal elegance: alligator or shell cordovan with vegetable tanning. For refined daily wear: calf leather with fine grain and natural patina development. For versatility and sports: grey cordura NATO or FKM rubber strap. The key is that the strap respects the Tangomat's minimalist philosophy: no excess, pure function.

How do I change the strap on the Nomos Glashütte Tangomat 637?

Strap change requires a delicate spring bar tool. Insert the flat tip into the slot beneath the lug, lift slightly to release the internal spring, and extract the bar. Repeat on the other side. Proceed with care to avoid scratching the satin-finished case. If inexperienced, contact an official Nomos service centre or Casati Milano atelier for professional replacement.

Is a 20mm aftermarket strap compatible with the Tangomat 637?

Yes, provided it respects the exact 20mm dimension and lug profile. Standard lug bars are 1.8mm in diameter. However, we recommend straps from specialised manufacturers who understand German design aesthetics and tolerance precision. Milan-crafted straps ensure construction quality and stitching that honour the case manufacturing standards.

How long does a leather strap last on the Nomos Glashütte Tangomat 637?

A quality leather strap (alligator, calf, cordovan with vegetable tanning) lasts 5–8 years of daily wear with proper care. Leather darkens, develops surface creasing and patina that testify to elegant ageing. Replacement becomes necessary when the lugs begin lateral movement in the strap seat or when the profile thins excessively. NATO and rubber straps last 10–15 years, as these materials age more slowly.

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