Jaeger-LeCoultre
Master Control 4118420— lug 20mm

The lug width of the Master Control 4118420 is 20 millimetres. This is the specific standard for the 40-millimetre case of this model. Always verify this measurement before ordering a replacement strap, as a different width will not fit correctly onto the case lugs.

For the understated aesthetics of the Master Control 4118420, the most recommended straps are alligator in dark brown tones (for a formal and luxurious result) and vegetable-tanned calf leather (for a patina that develops over time). Alternatively, black shell cordovan with a metal deployante buckle offers discrete elegance, whilst quality textile NATO straps allow more versatile combinations while maintaining the refined character of the case.

Strap replacement is achieved by removing the spring bars connecting the current strap to the case lugs. Using a spring bar tool, press downward on the small elastic pin and slide the pin out of the lug. Repeat the operation on both sides, then insert the new strap pins (ensuring they are 20 millimetres) into the lugs, taking care to align perfectly before releasing pressure.

Yes, the 4118420 strap is fully replaceable with quality aftermarket models, provided they respect the 20-millimetre lug width. Specialist manufacturers such as Milano Straps offer straps in alligator, calf, shell cordovan and technical materials, manufactured to construction standards equivalent to original Jaeger-LeCoultre products with the option to personalise choice of leather, colour and buckle.

The lifespan of a leather strap depends on the quality of the material, frequency of use and maintenance applied. A strap in excellent-quality alligator or shell cordovan typically lasts 3–5 years with regular use (four to five days per week) before showing signs of wear at critical areas, particularly where the strap bends at the buckle. Vegetable-tanned leather straps develop patina over time whilst maintaining structure, whereas synthetic materials have variable durability. The 18-month warranty offered by Casati Milano covers manufacturing defects during this period.