Discover Jaeger-LeCoultre's precision with the Master Control (ref. Q4138431), a distinctive model that balances proportion, precision, and presence. On the wrist, the case feels purposeful: crafted in stainless steel and measuring 40 mm in diameter, with a thickness of 12.05 mm, defined by a round silhouette. The caseback is open, and the crystal is sapphire, delivering water resistance to 5000 meters. Visually, the face is where character emerges: a silver tone with sunburst finish, framed by mixed hour markers, and dauphine hands. Mechanically, the watch prioritizes accuracy: the 759 caliber. Initial production year: 2025. The silhouette offers presence without excess, lending confidence in a range of situations. Finishing showcases disciplined attention to detail across facets, edges, and surfaces. For buyers researching specifications and real-world impressions, this reference stands out for coherent design, dependable mechanics, and lasting relevance within modern horology.