Longines · HydroConquest

Strap for HydroConquest 43 Automatic Stainless Steel - Yellow Gold / Blue / 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 diameter43 mm
ReferenceL3.782.3.96.9
FamilyHydroConquest
MovementLongines caliber L888.5 hours, minutes, seconds | date | chronometer
Year2022
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 L3.782.3.96.9

Selected for the 21 mm lug width · workshop selection

All 21 mm straps →

The HydroConquest L3.782.3.96.9, seen from the bench

The Longines HydroConquest L3.782.3.96.9 is a 43mm stainless steel diving watch with a black ceramic bezel, representing the evolution of Swiss underwater instruments from the 1960s. Powered by the L888.5 automatic movement with COSC chronometer certification, it offers water resistance to 300 meters and a 21mm lug width. The watch features hours, minutes, seconds, and date display, with no unnecessary complications.

Frequently asked questions

What is the lug width of the Longines HydroConquest L3.782.3.96.9?

The lug width is 21mm. Measured as the internal space between the two lugs (eyelets) from wall to wall. This specification is essential for selecting a compatible strap: 20mm straps will seat with excessive play, while 22mm straps will not fit. It is a non-standard width for civilian diving watches of 43mm diameter, requiring dedicated solutions.

Which strap is most suitable for the Longines HydroConquest L3.782.3.96.9?

African alligator with vegetable tanning is the natural choice for a diving instrument: it absorbs moisture, maintains flexibility after saltwater immersion, and develops patina naturally over time. Grained calf is a versatile alternative for daily urban and occasional underwater wear. Vulcanised rubber remains the most logical solution if you wear the watch in the sea: immediate drainage, rapid drying, UV durability.

How do you change the strap on the Longines HydroConquest L3.782.3.96.9?

The strap is secured via eyelets on the case lugs. Use a spring bar tool or fine pointed instrument: insert the pin into the eyelet hole with lateral pressure to compress the internal spring, remove the old strap, insert the new one ensuring the spring bar is correctly positioned. Avoid excessive force that could scratch the case.

What is the compatibility of an aftermarket strap for this lug width?

An aftermarket strap must have precisely 21mm lug width to seat without excessive play in the Longines eyelets. Generic or standard aftermarket straps (20mm or 22mm) are not compatible. Custom artisanal solutions ensure perfect fit and adjustable length for various wrist sizes.

How long does a leather strap last on the Longines HydroConquest L3.782.3.96.9?

A quality vegetable-tanned alligator strap lasts typically 3–5 years with daily wear, developing visible patina over time. Durability depends on: frequency of wear, exposure to saltwater/chlorine, leather maintenance (periodic cleaning, immediate drying after swimming). Calf straps have similar lifespan but require greater humidity attention. Casati Milano artisanal guarantee is 18 months for manufacturing defects.

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.

Request an appointment →

Casati Milano · Via XX Settembre 15, Milan · by appointment only