Strap for Fifty Fathoms Bathygraphe Quantième Annuel Black / Grey / Black NATO

The lug width of the Blancpain Fifty Fathoms 5071-1110-NABA is 23mm. This measurement is taken between the two horizontal spring bars positioned on the case lugs. To verify it correctly, use a digital calliper perpendicular to the case, measuring from inside to inside of the spring bar seatings. This width is critical for the visual balance between the 43mm case diameter and wrist comfort.

We recommend alligator straps (havana, black, cognac) for timeless elegance, vegetable-tanned calf leather (bordeaux, black, brown) for progressive patina development, or shell cordovan for natural rigidity and luminosity. Natural rubber straps are ideal if you use the watch for technical diving. Your choice depends on context: formal, sportive, or mixed wear.

Strap replacement on the 5071-1110-NABA involves removing the spring bars from the lugs using a dedicated spring bar tool. Position the tool beneath each bar, apply lateral pressure to release the internal spring, withdraw the bar from its seating, then replace the strap and reinsert the bars until you hear an audible click. Avoid excessive twisting that could deform the steel lugs.

Yes, the 5071-1110-NABA accommodates all aftermarket straps with 23mm lug width. Verify that the strap respects this width exactly: the spring bars must seat without play or overlap relative to the case sides. An artisanal-quality strap guarantees superior natural flexibility and temporal behaviour compared to industrial alternatives.

A high-quality artisanal leather strap—vegetable-tanned or alligator—lasts approximately 5–7 years with daily wear, provided it undergoes periodic maintenance (gentle cleaning, avoiding prolonged moisture, applying protective cream every 6–12 months). Natural vulcanised rubber offers greater resistance in humid and aquatic environments, lasting 7–10 years. Shell cordovan reaches 10+ years due to superior fibre density.