Strap for Senator Perpetual Calendar Stainless Steel Black / Rubber / Pin

The lug width of the Glashütte Original Senator 100-02-25-12-06 is 18 millimetres. This specification is determined by the physical distance between the lugs of the case where the strap is attached. You can verify this with a digital calliper by measuring the internal space between the attachment points. Any compatible strap must respect this measurement precisely, otherwise it will not insert correctly into the lugs.

There is no single 'best' choice, but rather several optimal options depending on context. An alligator strap with vegetable tanning represents the formal solution: it develops patina over time and creates aesthetic harmony with Glashütte finishing. Calf leather is the most versatile choice, suitable for professional and casual settings. NATO offers practicality for intensive use without compromising rigour. FKM rubber is ideal for active contexts. The choice depends on primary use and personal aesthetic preference.

Strap replacement is accomplished using the spring bars (lugs). Obtain a spring bar removal tool with flat-ended levers. Position the watch on a flat surface, insert the tool into the spring bar hole, apply gentle downward pressure to compress the internal spring, and extract the spring bar from the case. Repeat for the opposite spring bar. The strap will then come free. To install the new strap, insert the spring bars into the designated slots, maintaining light pressure until fully seated in the case holes. Verify that the strap is symmetrical and that the spring bars are completely secure.

Yes, numerous strap manufacturers produce models for 18mm lug width, including established brands and small-scale manufactures. Milano Straps offers a dedicated collection of 18mm straps, available in alligator, calf, NATO and rubber. Always verify that the strap is dimensioned for 18mm and that this specification is stated in the technical sheet: the spring bars must correspond to the case pitch (width that inserts into the lateral holes). Avoid generic non-dimensioned straps, as they may not fit correctly.

The lifespan of a leather strap depends on multiple factors: frequency of use, climate, exposure to moisture, type of tanning and construction quality. A quality alligator or calf strap (such as vegetable-tanned versions) typically lasts 3–5 years with moderate daily use. Frequent exposure to perspiration or water reduces durability. Leather develops natural patina over time, usage marks that increase character. When the leather begins to lose visible elasticity or the body becomes excessively thin, replacement is advisable. In the interim, an FKM rubber or NATO strap can serve as a practical alternative without compromising the watch.