Sinn · Instrument Chronographs

Strap for Pilot Chronograph 103 Classic

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

Lug width20 mm
Case diameter41 mm
Reference103Classic
FamilyInstrument Chronographs
MovementETA caliber 7753 hours, minutes, small seconds | date | Chronograph
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 Instrument Chronographs 103Classic

Selected for the 20 mm lug width · workshop selection

All 20 mm straps →

The Instrument Chronographs 103Classic, seen from the bench

The Sinn 103 Classic belongs to the Instrument Chronographs collection of the German brand. It mounts the automatic ETA 7753 caliber with hour, minute, small second, date and chronograph functions. The watch features 20mm lugs for the strap.

Frequently asked questions

What is the lug width of the Sinn 103 Classic?

The lug width of the Sinn 103 Classic is 20mm. This is the precise measurement between the two attachment pins on the case lugs. To verify, measure directly between the attachments: the value must correspond to 20mm to ensure compatibility with any aftermarket strap.

What is the best strap for the Sinn 103 Classic?

The choice depends on your use case. For elegant daily wear: vegetable-tanned leather or alligator. For humid or operational environments: vulcanised rubber with textured finish. For versatility and historical authenticity: rigid quality NATO fabric. All materials are available in 20mm width and provide secure grip and durability.

How do I change the strap on my Sinn 103 Classic?

Remove the spring bar pins using a dedicated spring bar tool (small forked extractor). Position the tool under the first pin, apply gentle downward and lateral pressure until it releases from the seat. Repeat for the second pin. Insert the new strap, aligning the holes with the pins, and press firmly until you hear a click. Always verify security before wearing.

Can I use an aftermarket 20mm strap on my Sinn 103 Classic?

Yes, provided the strap is certified for 20mm lug width. Quality bespoke makers manufacture straps with precise tolerances that guarantee compatibility without play. Avoid generic or approximate items. A quality strap has perforated holes or slots precisely aligned to specification.

How long does a leather strap last on the Sinn 103 Classic?

With proper care (air drying after moisture exposure, avoiding persistent rainfall), a taurine leather strap lasts 18–36 months. An alligator in vegetable tanning can reach 4–5 years. Longevity depends on wear frequency and environmental conditions. Vulcanised rubber has indefinite durability if protected from sustained direct UV exposure.

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