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Blancpain · Fifty Fathoms

Strap for Fifty Fathoms Titanium / Blue / Bracelet

Takes 23 mm straps. Verified lug width, the straps that fit this model, and answers to the most common questions.

Lug width

23mm
23 mm strapsAll Blancpain
Lug width23 mm
Case diameter45 mm
Reference5015-12B40-98
FamilyFifty Fathoms
MovementBlancpain caliber 1315 Hours, Minutes, Seconds | Date
CaseTitanium

Spring bar

Swiss Standard universal spring bars

The right category for this model · 316L steel, all lug widths 13–26 mm

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The Fifty Fathoms 5015-12B40-98, seen from the bench

The Blancpain Fifty Fathoms 5015-12B40-98 is the modern heir to a legendary 1953 design created by Jean-Jacques Fiechter for French Navy divers. This 45mm brushed titanium model features a unidirectional bezel, domed sapphire crystal, and screw-down crown, certified to 300 meters depth. The 23mm lug width accommodates the case diameter while maintaining structural robustness. Inside beats the Blancpain caliber 1315 automatic movement with oscillating balance wheel, displaying hours, minutes, seconds, and date.

Frequently asked questions

What is the lug width of the Blancpain Fifty Fathoms 5015-12B40-98?

The lug width is precisely 23mm. This measurement is taken between the two internal pins of the case lugs. To verify, use a digital calliper positioned perpendicularly between the internal lugs. Do not confuse this with the visible external space between the lugs: the technical specification that determines strap compatibility is solely the internal distance between the anchor points.

Which strap pairs best with the titanium Blancpain Fifty Fathoms?

For the brushed titanium case of the Fifty Fathoms, we recommend black alligator or vegetable-tanned calfskin in dark tones (mahogany, brown, black). Alligator provides noble contrast whilst enhancing the metallic patina; vegetable-tanned calfskin conveys tactile integrity with regular grain structure. Both materials maintain the instrumental seriousness of the dive watch without aesthetic compromises.

How do I replace the strap on the Blancpain Fifty Fathoms 5015-12B40-98?

Position the watch with the strap facing upward. Locate the anchor pins (spring bars) that connect the lugs to the case. Use a dedicated spring bar tool to compress the pin whilst removing the strap from the lug. Repeat on the opposite side. To install the new strap, insert the first lug onto the pin, compress the pin with the tool and secure the second side. Verify that both pins are completely locked.

Can I use a third-party strap on this Blancpain?

Yes, provided the strap is compatible with 23mm lug width (measured between internal pins). Artisanal third-party straps adapt perfectly to the Fifty Fathoms, respecting case proportions and materials (alligator, calfskin, NATO, structured rubber). Strap quality is not linked to the watch brand: it depends on construction craftsmanship and material selection.

How long does a leather strap last on a Blancpain Fifty Fathoms with regular use?

A quality artisanal leather strap (alligator, vegetable-tanned calfskin, shell cordovan) typically lasts 4–6 years with non-aggressive daily wear. Longevity depends on sun exposure, humidity, perspiration and maintenance frequency. A strap subjected to repeated immersions or prolonged saltwater contact deteriorates faster. Casati Milano offers an 18-month warranty on manufacturing defects and recommends annual preventative maintenance to extend material lifespan.

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