Jaeger-LeCoultre · Master Control

Strap for Master Control Calendar Stainless Steel / Silver / Bracelet

Takes 20 mm straps. Verified lug width, the straps that fit this model, and answers to the most common questions.

Lug width20 mm
Case diameter40 mm
ReferenceQ4148120 (aka: 4148120)
FamilyMaster Control
MovementJaeger-LeCoultre caliber 866AA Hours, Minutes, Small Seconds | Date, Day, Month | Moonphase
CaseStainless Steel

Spring bar

Swiss Standard universal spring bars

The right category for this model · 316L steel, all lug widths 13–26 mm

Straps for the Master Control Q4148120 (aka: 4148120)

Selected for the 20 mm lug width · workshop selection

All 20 mm straps →

The Master Control Q4148120 (aka: 4148120), seen from the bench

The Master Control is a classic Jaeger-LeCoultre timepiece that features the 866AA caliber with hour, minute, small seconds, full calendar, and moon phase indications. The Q4148120 reference features 20mm lugs and offers traditional Swiss watchmaking complications. The movement integrates date, day, month, and moon phase indicator functions in a balanced layout.

Frequently asked questions

What is the lug width of the Jaeger-LeCoultre Master Control Q4148120?

The lug width of the Jaeger-LeCoultre Master Control Q4148120 is 20 millimetres. This specific measurement represents the distance between the two spring bars that attach the strap to the watch case. It is a non-standard size that requires a conscious search for bespoke, compatible straps.

Which type of strap is best suited to the Master Control Q4148120?

The Master Control Q4148120, given its geometric elegance and constructive sobriety, pairs ideally with an alligator strap featuring vintage grain, shell cordovan with natural patina, or vegetable-tanned calf leather. For a more dynamic option, a rubber or NATO fabric strap in premium textile offers versatility whilst maintaining 20mm proportions.

How do I change the strap on the Jaeger-LeCoultre Master Control Q4148120?

Strap replacement requires extraction of the spring bars from the case lugs. It is recommended to use a dedicated tool (spring bar tool) to avoid damage to the metal. The procedure is identical to any other watch: place the watch on a soft surface, align the tool to the spring bar, apply gentle lateral traction until extraction, then proceed with the new strap. If inexperienced, consult the Casati Milano atelier.

Can I use an aftermarket strap compatible with the Q4148120?

Yes, provided the strap is constructed specifically for a 20mm lug width. Generic 20mm straps available online may present tolerance variations. The ideal approach is to entrust bespoke artisans such as Casati Milano, who construct made-to-measure straps with millimetre precision, ensuring perfect fit and construction quality worthy of the timepiece.

How long does a leather strap last on a Jaeger-LeCoultre Master Control?

The lifespan of a leather strap depends on material and usage. A quality alligator or shell cordovan strap, with regular maintenance and rotation with other straps, lasts an average of 5–8 years. A vegetable-tanned calf strap, more delicate, may require replacement every 3–5 years. Casati Milano guarantees 18 months against manufacturing defects, but longevity depends on wear caused by perspiration, humidity and solar exposure.

The next step

The right strap isn't chosen. It is built, together.

From the atelier appointment to delivery, every step is made for those who know that things done well take time. Rare leathers, one piece at a time, eighteen months of warranty.

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Casati Milano · Via XX Settembre 15, Milan · by appointment only