Strap for Flagship 40 Stainless Steel / White - Roman / Bracelet

The lug width of the Longines Flagship L4.984.4.21.6 is 21 millimetres. This is the precise distance between the case lugs. To verify compatibility with an aftermarket strap, measure the perpendicular distance between the lugs using a caliper or ruler: it must measure exactly 21mm.

The Flagship L4.984.4.21.6 accommodates multiple choices: an alligator with vegetable tanning delivers classic elegance; smooth grain calf offers versatility and develops rich patina over time; textured rubber provides practical daily-wear durability; shell cordovan in burgundy tones adds character whilst maintaining restraint. Your choice depends on intended use and aesthetic preference.

Remove the spring bars connecting the strap to the case using a spring bar tool. Insert the tool into the lateral hole of the spring bar, apply gentle pressure to create space, then extract the bar. With the lugs now free, remove the old strap and insert the new one, ensuring the bars align correctly before pressing until you hear the locking click.

Yes, any strap with 21mm lug width is compatible with the Longines Flagship L4.984.4.21.6, provided the spring bars match in length and diameter (typically 1.6mm on this model). Always verify that the strap thickness does not exceed 3–4mm total to ensure proper fit on the case. Artisanal straps from milanostraps.it are available in numerous finishes for this size.

Leather strap longevity depends on material quality, usage patterns and maintenance. A vegetable-tanned alligator or calf strap with artisanal construction resists 3–5 years under moderate daily wear; with occasional use, it can last 7–10 years. Rubber delivers greater durability (5–8 years with intensive use). The natural ageing process is part of the character: patina development is evolution, not degradation. Casati Milano's warranty covers manufacturing defects for 18 months.