Strap for Portofino Chronograph Laureus

The lug width of the IWC Portofino IW3910-19 is 20mm. This dimension represents the ideal proportional ratio between the 42mm case diameter and the total bracelet length. To verify correct compatibility of an aftermarket strap, measure precisely from hole to hole of the original spring bar. If you already own a compatible strap, the reference code engraved on the buckle will indicate the 20mm measurement.

The ideal material depends on intended use. For formal elegance, alligator with vegetable tanning is the supreme choice thanks to its natural grain and lightness. Vegetable-tanned calf offers robustness and develops characteristic patina over time. Shell cordovan provides absolute wear resistance and sober luxury. For sport or summer wear, vulcanised elastomers or technical textiles enhance the chronograph's tool-watch nature. Absolute black, cognac brown, and deep navy blue are the most balanced chromatic pairings with the Portofino's white dial.

Strap replacement is performed using a spring bar tool, a specialised two-pointed instrument. Insert the tip into the space between the lug and spring bar, applying gentle inward pressure to compress the spring. Simultaneously, pull the lug outward. Once extracted, repeat the operation on the opposite side. For installation of the new strap, compress the spring bar, align the lug to the hole, and release pressure gradually. If inexperienced, Casati Milano can perform the operation by appointment.

Any strap with a 20mm lug width is compatible with the Portofino IW3910-19. The range offered by Milano Straps includes straps in alligator, calf, shell cordovan, elastomer, and technical textile, all handcrafted and customisable in length, initials, and thread colour. All models feature a standard quality spring bar that fits perfectly to the original case lugs.

The lifespan of a leather strap depends on material, tanning method, and intensity of use. An alligator strap with vegetable tanning lasts approximately 3–5 years of daily wear; vegetable-tanned calf 2–4 years; shell cordovan up to 7–10 years due to its extraordinary resistance. Constant exposure to water, humidity, and UV rays reduces longevity. Casati Milano guarantees 18 months on all atelier-made straps and offers restoration and reconditioning services to extend the accessory's lifespan.