Strap for Modello Tre U3-A

The lug width of the Unimatic Modello Tre U3-A is 22mm. This dimension, measured between the two attachment points on the case, determines compatibility with aftermarket straps. Precise measurement is essential: position a digital calliper between the inner base of one lug and the other to obtain the exact 22mm value.

There is no universally absolute choice: it depends on usage and aesthetic preferences. To emphasise formal minimalism, black alligator leather or brown vegetable-tanned calf create precise visual harmonies. To emphasise tool-watch vocation, a technical fabric NATO in olive drab or charcoal, or an FKM rubber strap remain ideal. Consider the context of use: formal environments require leather, aquatic situations suggest rubber.

Changing the lug on a U3-A requires the use of a spring bar tool, the specific instrument for extracting the spring bars that anchor the strap to the case. Insert the tip of the spring bar tool under the spring bar (the small metal pin protruding from the lugs), apply gentle downward pressure to release the pin, remove the old strap and insert the new one, aligning one lug first, then pressing the spring bar into the second seat. A simple operation but one that requires care not to scratch the lugs.

Yes, all straps with 22mm lug width are compatible with the U3-A. Milano Straps offers a specialist collection of leather straps (alligator, calf, shell cordovan), NATO fabric, technical rubber, all available in 22mm width. Compatibility is guaranteed when the lug width matches exactly: always verify before purchase.

Durability depends on intensity of use, type of leather and maintenance. A vegetable-tanned leather strap, subjected to moderate daily use, maintains full functionality for 3-5 years, developing a patina that enriches its aesthetic appeal. Vegetable tannins tend to craze visibly but remain wearable. Alligator, more resistant to tension, can last 5-8 years. FKM rubber has similar longevity but degrades differently: it gradually loses elasticity. Maintenance—gentle cleaning, avoiding prolonged humid environments—significantly extends the useful life of any leather strap.