Laco · Pilot Watches

Strap for Pilot Watch Basic Altenburg Stainless Steel / Black

Takes 18 mm straps. Verified lug width, the straps that fit this model, and answers to the most common questions.

Lug width18 mm
Case diameter39 mm
Reference861991
FamilyPilot Watches
MovementETA caliber 6497-1 hours, minutes, small seconds
Year2019
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 Watches 861991

Selected for the 18 mm lug width · workshop selection

All 18 mm straps →

The Pilot Watches 861991, seen from the bench

The Laco 861991 Pilot Watch Basic Altenburg is a contemporary reinterpretation of German Beobachtungsuhr aviation navigation instruments from WWII. It features a 39mm stainless steel case with a minimalist dial, Arabic numerals, and an ETA 6497-1 manual Swiss movement with three subdials. The watch maintains authentic proportions with an 18mm lug width, a rare specification reflecting original flight instrument standards.

Frequently asked questions

What is the exact lug width of the Laco Pilot Watches 861991?

The lug width of the Laco 861991 is precisely 18mm. This measurement is taken between the two spring bar pins, measured perpendicularly to the case. It is essential to verify this dimension with millimetre accuracy, as straps dimensioned for 20mm would be too wide and cause excessive movement, whilst 16mm would be insufficient. If you do not have a digital calliper, please contact our team directly for verification before purchase.

Which type of strap is most suitable for the Laco 861991?

The Laco 861991, maintaining authentic historical proportions as a pilot watch, pairs exceptionally well with vegetable-tanned leather straps of moderate thickness (3-5mm total). A havana brown or cognac-coloured strap creates aesthetic continuity with its Germanic heritage. Alternatively, a dark grey NATO strap or a gummed deployante offers functional practicality whilst maintaining technical aesthetics. It is inadvisable to exceed 5mm total thickness at the lug attachment, as this would compromise the visual proportions of the model.

How do I replace the strap on the Laco 861991?

Strap replacement requires the removal of the lateral spring bar pins that connect the lugs to the case. Obtain a spring bar tool and position it in the side slots of the case, then apply inward pressure to release the pin. Once the old strap is removed, insert the pins of your new 18mm-dimensioned strap into the slots, ensuring perfect alignment. Press gently until you hear or feel the click of engagement. If you are not confident with this procedure, our team is available for technical support.

Is an 18mm aftermarket strap fully compatible with the Laco 861991?

Yes, any strap precisely dimensioned at 18mm is fully compatible with the Laco 861991, regardless of brand. Variables include construction quality, leather type or material, thickness, and aesthetic design. MilanoStraps.it straps are manufactured with premium materials—vegetable-tanned leather, alligator skin, natural rubber—and guarantee millimetre tolerances ensuring perfect accommodation without movement. The critical factor is that the strap does not exceed 5mm total thickness at the lug attachment, as this could interfere with case closure.

What is the lifespan of a vegetable-tanned leather strap on the Laco 861991?

The durability of a vegetable-tanned leather strap depends on intensive use, climatic conditions, and maintenance practices. On average, an artisanal quality strap used daily maintains structural integrity between 3-7 years. Vegetable tanning is not a durability shortcoming; rather, it develops a natural patina that imparts character and aesthetic depth. To extend strap life, avoid prolonged water immersion, clean regularly with a damp cloth, and occasionally apply conditioning treatment specific to vegetable-tanned leather. Unlike synthetic leather, a vegetable-tanned strap can be regenerated through professional reconditioning, offering a second lifecycle to the product.

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