Strap for Senator Perpetual Calendar Stainless Steel / Black / Alligator / Folding

The lug width is 20 millimetres. This is the distance between the two spring bars that protrude from the case lugs. This measurement is essential when purchasing a compatible strap: a 20mm strap will fit correctly into the case lugs without forcing and permits free rotation of the strap around the spring bars.

The choice depends on intended use and aesthetic preferences. For formal contexts, a natural dark brown alligator strap enhances the elegance of the stainless steel case; for daily wear, a vegetable-tanned calf strap develops a fascinating patina over time; for sporting or summer contexts, a heavy cotton NATO or FKM rubber strap provides practicality without compromising the Senator's proportions.

The strap is secured to the case via two spring bars, one per lug. To remove it, a specialised tool (spring bar tool) is required, which compresses the spring bar from beneath the lug, creating space to extract the spring bar from its housing. Once the old strap is removed, the new 20mm strap is inserted simply by aligning the strap holes with the spring bars and allowing the bars to return to position. The operation takes several minutes and can be performed independently or by a qualified watchmaker.

Yes, any artisanal strap with a 20mm lug width is compatible with the Senator 100-02-25-12-05. High-quality aftermarket straps do not compromise the watch's function and allow aesthetic variation without modifying the case or movement. It is advisable to verify that the strap has appropriate thickness (6–8 millimetres) and spring bar lugs suitable for the case lug depth.

A quality leather strap (alligator, vegetable-tanned calf) typically lasts between 3 and 7 years of daily wear, depending on exposure to moisture, heat, and mechanical stress. Frequency of maintenance (cleaning, conditioning with neutral oils) significantly extends durability. FKM rubber straps resist degradation for 5–10 years. Replacement is an economical operation that allows renewal of the watch's appearance without significant investment.