Longines · Flagship

Strap for Flagship 40 Stainless Steel / Black - Diamond / Bracelet

Takes 21 mm straps. Verified lug width, the straps that fit this model, and answers to the most common questions.

Lug width21 mm
Case diameter40 mm
ReferenceL4.984.4.57.6
FamilyFlagship
MovementLongines caliber L888.5 hours, minutes, seconds | date | chronometer
Year2022
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 Flagship L4.984.4.57.6

Selected for the 21 mm lug width · workshop selection

All 21 mm straps →

The Flagship L4.984.4.57.6, seen from the bench

The Flagship represents one of Longines' classic collections with a strong tradition in the dress watch segment. It is equipped with the automatic L888.5 caliber with chronometer certification and hour, minute, second and date functions. The case features 21mm lugs for the strap.

Frequently asked questions

What is the lug width of the Longines Flagship L4.984.4.57.6?

The lug width is precisely 21 millimetres. This specific measurement is essential for selecting a compatible strap. Measure by positioning a digital calliper perpendicular to the case between the spring bar attachment points, centred on the lug. A strap undersized will leave visible gaps; an oversized strap will force the passage, damaging the case attachments.

What is the best strap for the Longines Flagship L4.984.4.57.6?

There is no single 'best' choice; rather, informed selections based on intended use. Mississippi alligator is the dressy option, with a fine natural grain complementing the silver dial. Calf leather with vegetable tanning offers durability and character-rich patina development. Shell cordovan appeals to purists: it forms a polished shell and ages with personality. For casual contexts, heavyweight canvas NATO adds dynamism. FKM rubber suits summer wear.

How do I change the strap on the Longines Flagship L4.984.4.57.6?

The Flagship uses standard spring bar attachments. To remove the strap, use a spring bar tool or extraction pin to slide the spring bar back on one side of the case, gently pulling the lug outward. Repeat on the opposite side. To install, align the lug with the case holes and push gently until the spring bar clicks into place. Verify the strap sits perpendicular to the case.

Is an aftermarket strap compatible with the Longines Flagship L4.984.4.57.6?

Yes, provided the lug width is precisely 21 millimetres. Any quality strap with 21mm lugs and standard spring bars pairs seamlessly with the Flagship. Prolonged attempts to force undersized or oversized straps irreversibly damage the case attachment finishes. We recommend accurate measurements and certified raw materials.

How long does a natural leather strap last on a watch like the Longines Flagship?

Longevity depends on leather quality, frequency of wear, and maintenance. A Mississippi alligator or shell cordovan strap worn daily on a Flagship maintains structural integrity for 4–6 years. Vegetable-tanned calf lasts approximately 3–5 years with regular moisture exposure. Stitching is the critical failure point: if executed in waxed cotton or silk thread, it may fail before the leather itself. An 18-month artisanal warranty covers construction defects, not natural wear, which nonetheless remains visually characteristic.

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