Archimede · Pilot

Strap for Pilot Chronograph Staineless Steel / Black

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
ReferenceUA7939-C1.1
FamilyPilot
MovementETA caliber 7750 Hours, Minutes, Small Seconds | Date, Day | 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 Pilot UA7939-C1.1

Selected for the 20 mm lug width · workshop selection

All 20 mm straps →

The Pilot UA7939-C1.1, seen from the bench

The Archimede Pilot UA7939-C1.1 is a stainless steel chronograph watch with a 42mm case and 20mm lug width, featuring an ETA caliber 7750 automatic movement. The black dial displays Arabic numerals and a central arrow hand, characteristic of German Fliegeruhr design. It offers three subdials for hours, minutes, and small seconds, plus date and day windows, with 200 meters water resistance. The watch represents contemporary evolution of WWII-era pilot watches with functional design principles.

Frequently asked questions

What is the exact lug width of the Archimede Pilot UA7939-C1.1?

The lug width of the Pilot is 20 millimetres. This measurement refers to the horizontal distance between the two lateral lugs on the case where the strap is installed. To verify, use a digital calliper or millimetre ruler: the measurement must be exact to ensure compatibility without play and without forcing during pin insertion.

Which strap pairs best with the black dial of the Archimede Pilot?

The ideal strap depends on intended wear context. For a classic and sophisticated result, vegetable-tanned leather in cognac or shell cordovan in deep burgundy create narrative contrast with the black. For minimalist and tactical styling, NATO in light grey canvas or off-white calf guarantee monochromatic coherence. For professional environments with humidity exposure, vulcanised black rubber with fine grain offers superior waterproofing and durability.

How do I change the strap on the Archimede Pilot UA7939-C1.1?

The strap is replaced by depressing the lateral pins from their seats. Position the watch on a soft surface (cotton cloth), then use a spring bar tool to apply gentle pressure to the spring support mechanism of the first pin. Once the first pin is extracted, you can remove the old strap and insert the new one while keeping the pin partially extracted. Finally, reinsert the pin into the opposite seat and verify secure anchorage. Avoid forced movements that could scratch the case.

Are there aftermarket straps compatible with the 20mm lug width of the Pilot?

Yes, 20mm lug width is a standard measurement across numerous market segments. Milanostraps.it offers artisanal leather straps from various sources (Italian, French), NATO in military-grade canvas, technical rubber straps, all with 20mm lugs. It is important to verify that the strap is specifically declared for 20mm and that construction quality meets professional standards, avoiding generic straps from unverifiable sources.

What is the lifespan of a natural leather strap for the Pilot?

A high-quality vegetable-tanned leather strap, used with rotation (alternating at least two straps), lasts an average of 4–6 years before replacement is necessary. Longevity depends on exposure to humidity, salt-infused perspiration, frequency of use and maintenance care. Vegetable tanning develops patina and natural cracking over time: this is an expected process, not degradation. A calibrated calf strap maintains stable aesthetic condition up to 5 years with regular wear; cordovan, given superior fibre density, can extend this window to 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