Longines · HydroConquest

Strap for Hydroconquest GMT 41 Stainless Steel / Green / 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 diameter41 mm
ReferenceL3.790.4.06.6
FamilyHydroConquest
MovementLongines caliber L844.4 Hours, Minutes, Seconds, Additional 24 Hour Hand (adjustable) | Date
CaseCeramic, Stainless 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 HydroConquest L3.790.4.06.6

Selected for the 21 mm lug width · workshop selection

All 21 mm straps →

The HydroConquest L3.790.4.06.6, seen from the bench

The Longines HydroConquest L3.790.4.06.6 is a 41mm stainless steel diving watch with ceramic bezel, combining 1960s diving heritage with contemporary proportions. Powered by the Longines L844.4 automatic movement featuring GMT function, date window, and chronometric certification, it offers 300-metre water resistance suitable for recreational diving. The 21mm lug width is critical for strap compatibility and must be verified before purchase to ensure proper fit and proportion.

Frequently asked questions

What is the lug width of the Longines HydroConquest L3.790.4.06.6?

The lug width of the Longines HydroConquest L3.790.4.06.6 is 21mm. This measurement represents the internal space between the lugs where the strap is fitted. Compatibility verification is essential before purchasing an aftermarket strap, as this model tolerates no variations in dimensional accuracy.

Which strap do you recommend for the Longines HydroConquest L3.790.4.06.6?

Choice depends on intended use. For formal occasions, we recommend alligator in mahogany brown or cognac: it develops natural patina over time whilst maintaining elegance. For robust daily wear, Italian vegetable-tanned calf offers pronounced texture and visible ageing. For intensive diving activities, vulcanised rubber or canvas NATO straps deliver absolute practicality and zero maintenance requirements.

How do you change the strap on the Longines HydroConquest L3.790.4.06.6?

Strap changing requires a specialist tool (spring bar remover) or a thin screwdriver to extract the lateral pins. Position the watch on a soft surface, insert the pin from one side with precision, remove the worn strap, and seat the new one sequentially. We recommend entrusting this procedure to a specialist atelier to prevent case scratches: Casati Milano offers this service by appointment in Milan.

Are 21mm straps from other manufacturers compatible with the Longines HydroConquest L3.790.4.06.6?

Yes, provided the lug width is precisely 21mm and the constructive thickness is proportionate to the 41mm case. A generic 21mm strap of inferior quality may exhibit slippage or instability. MilanoStraps selects only straps verified for mechanical and aesthetic compatibility with this model, guaranteeing zero tolerance on width and spring bar housing.

How long does a natural leather strap last on the Longines HydroConquest L3.790.4.06.6?

Durability depends on intensity of wear and maintenance routine. An alligator or Italian vegetable-tanned calf, with moderate daily use and periodic cleaning, lasts 18–24 months before replacement is necessary. Constant exposure to water, perspiration, and humidity significantly shortens serviceable life. Vulcanised rubber and NATO straps, conversely, exceed 3–4 years of intensive use without aesthetic degradation. Casati Milano provides an 18-month warranty on all custom straps.

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