Strap for Mission Timer U200 EZM 8

The lug width of the Sinn 1012.010 is precisely 18 millimetres. This measurement is historical and reflects the construction standards of diving watches from the generation preceding the 1980s. The width is measured between the upper lugs that connect the case to the strap, using a digital calliper positioned perpendicular to the lugs themselves.

The choice depends on the operational use of the watch. For frequent technical use in marine environments, FKM rubber (Viton) is the definitive solution: it resists salt, does not absorb water, and remains thermally stable. For mixed land-water use, a NATO in Cordura nylon or a vegetable-tanned calf leather treated with specific protective oils offers equilibrium between practicality and elegance. Shell cordovan is inadvisable: its permeable fibrous structure degrades rapidly when exposed to salt water.

The strap is replaced using a dedicated spring bar removal tool. Position the flat end of the tool under the spring bar on the case-back side, applying gradual pressure until the bar is released from its seat. Repeat for both upper bars. To install the new strap, align the strap holes with the bars, then reinsert the bars into their seats using the same tool, ensuring they click completely into position. Verify that the strap is evenly distributed on both sides of the case.

Yes, compatible straps exist, but the 18-millimetre measurement sits in an intermediate range between 16 and 20 millimetres, making the search more specialised than for standard 20 or 22 millimetre sizes. The best results come from craftspeople offering bespoke commissions, such as Milanese ateliers providing complete personalisation. Alternatively, some international vintage strap suppliers offer stock specifically designed for watches from the 1970s and 1980s generation.

The lifespan of a leather strap varies significantly depending on the material, treatment, and operational environment. A vegetable-tanned calf leather with proper protective treatment withstands 3–5 years of frequent use under normal terrestrial conditions. If the watch is frequently used in marine environments or subjected to diving, durability reduces to 12–18 months, as sea salt and UV exposure degrade the fibres, accelerating ageing. An FKM rubber strap resists 5–7 years before requiring replacement, with degradation primarily aesthetic rather than structural.