This is the legendary El Primero Zenith El Primero Winsor Annual Calendar, reference 03.2070.4054/02.C711, a watch that beautifully merges the brand's most celebrated innovation with contemporary aesthetic flair. At the heart of this watch lies the reason for its fame: the El Primero automatic chronograph movement. This is the original high-frequency integrated chronograph calibre, first conceived in 1969 and renowned for its precision, durability, and smooth sweeping chronograph hand that measures elapsed time to 1/10th of a second. The "Open" designation refers to the captivating aperture at 10 o'clock, offering a revealing glance at the star-shaped oscillating weight and the finely finished components of this legendary engine. It's a dynamic display of mechanical artistry. The watch presents a classic yet assertive 42mm stainless steel case, offering a substantial and luxurious presence on the wrist. The polished and brushed finishes create a sophisticated play of light. Surrounding the dial is a fixed steel tachymeter bezel, allowing for speed calculations—a classic function for a racing-inspired chronograph. The watch is operated via a signed push-piece crown and two finely crafted chronograph pushers, offering a precise and satisfying tactile response. This timepiece is fitted with a high-quality black alligator leather strap, secured by the original Zenith stainless steel double-folding clasp, ensuring comfort and security.