Strap for Master Collection 34 Moonphase Stainless Steel / Blue-Diamond / Bracelet

The lug width of the Longines Master Collection L2.409.4.97.6 is 18mm. This measurement represents the internal distance between the spring bar pins where the strap attaches to the case. To verify this dimension, measure the inner spacing on the lugs of this 34mm watch using a calliper or rigid ruler: it must correspond exactly to 18mm to ensure compatibility and proper ergonomics.

The ideal strap for this model is crafted from high-quality alligator or calf leather, preferably in brown, cognac, or black tones. These materials enhance the classical elegance of the Master collection and complement the white lacquer dial. For greater daily versatility, a vegetable-tanned leather strap maintains Longines' construction philosophy. Canvas NATO straps are advisable only for casual-sportive contexts.

To change the strap, use a high-quality spring bar tool. Position the watch horizontally in a stable holder. Insert the flat tip of the tool beneath one of the side pins, applying gentle and consistent upward pressure to compress the internal spring. Once the pin is freed, extract the old strap. Repeat on the opposite side. Insert the new pins (18mm lug width) into your replacement strap and secure them to the case using the same procedure in reverse, verifying mechanical lockage.

Yes, any aftermarket strap with 18mm lug width is mechanically compatible. However, to preserve aesthetic and construction integrity, we recommend artisanal leather straps from specialised suppliers. Always verify that the pins are removable and that the inner shoulder of the strap does not exceed 18mm in width, to avoid friction or detachment.

Leather strap durability depends on daily usage, material quality, and tanning method. Premium alligator or calf leather with vegetable or chrome tanning lasts approximately 4–7 years with rotation among multiple straps. If worn daily without breaks, lifespan reduces to 2–3 years due to natural wear (creasing, fading, buckle dimming). The Casati Milano 18-month warranty covers manufacturing defects; preventive buckle replacement extends strap life by a further 2–3 years.