Strap for 1858 Geosphere Stainless Steel / Black / NATO

The lug width of the Montblanc 1858 117837 is 20mm. This dimension is the standard for this model and determines compatibility with any aftermarket strap. It is essential to use a digital calliper to verify the measurement correctly, positioning it on the inner surface of the lug, between the two spring bar holes of the original strap.

The Montblanc 1858 117837, with its ceramic and steel case, pairs perfectly with straps in alligator leather with vegetable tanning (which develop patina over time), full-grain calf, dense cotton NATO, or FKM rubber. Dark brown alligator amplifies the sobriety of the ceramic bezel, whilst sand-coloured calf generates interesting luminous contrast with the world time dial.

To change the strap on the 117837, you must remove the spring bars positioned laterally on the sides of the lug. Use a dedicated spring bar tool to gently push the spring and slide it out from the hole, then remove the original strap. Insert the new 20mm strap by aligning the holes with the spring bars, press until it clicks and verify correct securing.

Yes, the Montblanc 1858 117837 accepts any artisanal or industrial strap with a 20mm lug width. Artisanal straps in alligator, shell cordovan, calf or cotton, crafted with vegetable tanning, offer higher quality alternatives to standard factory straps. Compatibility is guaranteed by the correct lug width: no adaptation is necessary.

The lifespan of a leather strap depends on the quality of tanning and daily use. An alligator or calf strap with vegetable tanning, with proper maintenance (annual conditioning with natural oils), lasts approximately 5-7 years of regular wear. FKM rubber has a similar lifespan. The important thing is to dry the strap quickly after water contact and apply protective cream periodically to preserve leather flexibility.