Zenith, EL PRIMERO, model: 03.2170.4613 / 21.C714, automatic mechanical movement, stainless steel, case diameter: 40mm, single case. With a diameter of 40 millimeters, it features a stainless steel case and a black radial dial. The most distinctive feature is the openwork window at the 9 o 'clock position, allowing a direct view of the operation of the high-frequency movement's balance wheel. This is also the origin of the "Happy" series. The bar hour markers are paired with luminous hands, and there is a date window at the 3 o 'clock position. The overall style combines the elegance of formal wear with the mechanical feel of sports watches. Paired with a black alligator leather strap, it is water-resistant to 100 meters and can handle both daily wear and light sports scenarios.