Strap for Conquest 39 Automatic Stainless Steel / Black / Bracelet

The lug width of the Longines Conquest L3.776.4.58.6 is precisely 19mm. This measurement must be respected when selecting an aftermarket strap. To measure it accurately, position a calliper between the two inner lugs of the case where the strap attaches: the distance from one lug to the other is exactly 19mm.

For the Conquest L3.776.4.58.6, American alligator of museum-grade quality is the most harmonious choice: the tight grain enhances the steel case without visually overloading the wrist. Alternatively, vegetable-tanned calf leather offers immediate comfort and develops a natural patina over time. For more informal daily wear, a canvas and rubber nato provides practicality and durability.

The strap is replaced using a spring bar tool or lever for the attachments. Place the watch on a soft surface (microfibre cloth), locate the side spring bar attachments on the case back, insert the tool under the attachment and gently pull outward to release the old strap. Repeat on the second side, then insert the new strap by aligning the holes with the spring bars until they click into place.

Yes, any strap with a 19mm lug width is fully compatible with the Conquest L3.776.4.58.6. Quality aftermarket straps (constructed from vegetable-tanned leather, alligator, or isothermal rubber) meet the same dimensional precision as original Longines straps and often offer a wider range of aesthetic choices.

A quality leather strap (alligator, vegetable-tanned calf, shell cordovan) typically lasts 3–5 years with regular wear, depending on exposure to moisture, perspiration, and direct sunlight. Museum-grade alligator can last 10–15 years. Regular maintenance (drying after perspiration, avoiding prolonged humidity) extends longevity. Rubber straps typically resist wear for 5–8 years before losing elasticity.