Longines · HydroConquest

Strap for HydroConquest 41 Automatic Stainless Steel / Ceramic / Grey / Rubber

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
ReferenceL3.781.4.76.9 (aka: L37814769)
FamilyHydroConquest
MovementLongines caliber L888.2 Hours, Minutes, Seconds | Date
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 HydroConquest L3.781.4.76.9 (aka: L37814769)

Selected for the 21 mm lug width · workshop selection

All 21 mm straps →

The HydroConquest L3.781.4.76.9 (aka: L37814769), seen from the bench

The Longines HydroConquest L3.781.4.76.9 is a 41mm automatic dive watch powered by the Longines L888.2 caliber, based on the ETA 2824-2 movement. The stainless steel 316L case features a screw-down crown at 9 o'clock and water resistance to 300 meters. With a 21mm lug width, this instrument combines functional design and corrosion resistance, featuring hours, minutes, seconds and date functions without unnecessary complications.

Frequently asked questions

What is the lug width of the Longines HydroConquest L3.781.4.76.9?

The lug width is 21mm. This measurement is specific to the HydroConquest model and ensures structural robustness of the case and proper compatibility with sports straps, including neoprene options. You can verify it using callipers to measure the distance between the two lug pins.

What is the best strap for the Longines HydroConquest L3.781.4.76.9?

Selection depends on intended use: for daily elegance, we recommend Nile alligator with vegetable tanning (cognac or dark brown); for versatility, calf leather or shell cordovan; for diving and sports, vulcanised rubber or NATO fabric in navy blue or black. A deployant clasp increases security on a dive watch.

How do I change the strap on the Longines HydroConquest L3.781.4.76.9?

Remove the watch from your wrist. Using a spring bar tool, insert the small fork underneath the lug pin you wish to replace, lifting slightly to extract it from the case. Repeat on the opposite side. To install the new strap, reverse the process by inserting the pin through the new strap holes and into the case until it clicks securely. For a bespoke experience, the Casati Milano atelier can perform the change with personal consultation.

Can I use an aftermarket 21mm strap on this watch?

Yes, any strap with a 21mm lug width is compatible. Milanostraps.it offers an extensive range of artisanal 21mm straps, customisable in leather, colour, dimensions, and stitching thread. We recommend selecting thickness and material consistent with your use case (softer leather for elegance, rubber or NATO for water sports).

How long does a leather strap last on a Longines HydroConquest L3.781.4.76.9?

A quality leather strap (vegetable-tanned alligator, calf leather, shell cordovan) lasts 3–5 years with daily wear. Longevity depends on use: exposure to salt water, perspiration, and humidity reduce lifespan. For frequent diving, favour rubber or NATO. Casati Milano straps include an 18-month warranty and can be easily refurbished or replaced.

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