A. Lange & Söhne
Lange 1 101.539— lug 20mm

The Lange 1 ref. 101.539 features a lug width of 20 mm. This dimension is measured between the two horizontal spring bar holes on the case lugs. Always verify compatibility by measuring the pins on your specific watch directly, rather than estimating from the visual width of the original strap.

For the white gold Lange 1, natural alligator in dark brown remains the traditional and most coherent choice with Saxonian design philosophy. Alternatively, vegetable-tanned calf leather offers a warmer, more refined surface. Shell cordovan is not recommended for this 20 mm lug width, as its inherent thickness prevents optimal visual proportions at this gauge.

Changing the Lange 1 strap requires a precision spring bar tool and careful manual handling. The two lateral pins must be gently compressed inward to release from the lug seats. We recommend working on a soft surface (felt) to avoid scratches. If uncertain, consult a specialist watchmaker or book a session with Casati Milano's Milan atelier by appointment.

Yes, any strap with a 20 mm lug width is physically compatible. However, to preserve the aesthetic character of the Lange 1, materials should align with haute horlogerie standards: alligator, vegetable-tanned calf, or premium grade leather. NATO or rubber Tropic straps, whilst compatible, contradict the formal Saxonian design language.

Durability depends on frequency of use and leather quality. A natural alligator strap with traditional vegetable tanning typically withstands 4–6 years of daily wear, developing characteristic patina over time. Calf and standard leather straps offer similar lifespan. Frequent exposure to moisture, direct sunlight, and perspiration reduces longevity. A shell cordovan strap, if still workable at 20 mm, can exceed 10 years of service.