Longines
Longines HydroConquest 41 Strap Size — 21mm Lug Width
The Longines HydroConquest 41 has a 21mm lug width, so it takes a 21mm watch strap.
Lug width21mm
| Lug width | 21 mm |
|---|---|
| Case size | 41 mm |
| Lug-to-lug | 49 mm |
| Thickness | 12.5 mm |
| Spring bar Ø (typical) | 2.0 mm |
| End type | Straight |
Which reference do you have?
Similar-looking models can take different straps. Your reference number is on the case back or your papers.
| Model | Case | Strap |
|---|---|---|
| HydroConquest 41 (L3.781) | 41mm | 21mm |
| Other HydroConquest sizes | 39–43mm | Check your reference |
Strap styles that fit
- NATO / Zulu21mm fits if the strap's thickness clears the case under the bars.
- PerlonWoven pass-through, 21mm.
- 2-piece leatherStraight ends fit flush.
- Rubber / siliconeDivers & sports fit well.
- Milanese / meshStraight-end 21mm mesh fits.
- Metal braceletNeeds 21mm end-links shaped for this case.
▲ 21mm on the 41mm (L3.781) references; check other case sizes separately.
Fit & sizing notes for the HydroConquest 41
- Width: buy 21mm straps. Tapered straps listed as 21/19mm or 21/17mm fit too; only the first number has to match. See strap sizes explained.
- Spring bars: 21mm long, about 2.0mm diameter (spring bar sizes).
- Odd size: 21mm straps are harder to find; a 20mm strap fits with a small gap, but never go wider. Odd lug width options.
- Wrist fit: at 49mm lug-to-lug it should sit within the top of wrists from about 16.3cm up (rule of thumb: lug-to-lug under ~30% of wrist size). That's longer than 81% of the watches in our index. See what size watch suits your wrist.
- Strap thickness: at 12.5mm thick it's mid-thickness, so most straps suit it; padded leather and NATOs both balance well.
Sources & corrections
Correction, 24 October 2026: This page previously listed 20mm. The 41mm HydroConquest (L3.781) is 21mm.
Lug width checked against: WatchBase: HydroConquest 41 L3.781. Last checked 24 October 2026.
Spec wrong for your watch? Send us a correction with your reference number.
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Longines HydroConquest 41 — strap questions
What size strap does the HydroConquest 41 take?
The Longines HydroConquest 41 has a 21mm lug width, so you need a 21mm watch strap.
Will any 21mm strap fit the HydroConquest 41?
Most will. Width is the main thing to match, but also check that the strap's spring-bar holes suit the bars, and that the strap is thin enough to clear the case between the lugs. A metal bracelet needs 21mm end-links made for this model.
What spring bar size does the HydroConquest 41 use?
21mm long and about 2.0mm in diameter (a typical figure; measure the original bar to be sure).
Is the HydroConquest 41 good for strap swapping?
Yes. With standard 21mm spring-bar lugs, NATO, leather, rubber and mesh straps can all be fitted with a spring-bar tool.