Chronomaster Sport Skeleton

ZENITH UNVEILS A SKELETONIZED VERSION OF THE CHRONOMASTER SPORT

When ZENITH introduced the El Primero in 1969, it did more than launch the world’s first automatic, integrated high-frequency chronograph. It established a new standard of precision in mechanical watchmaking. Beating at 5Hz, 36 000 vibrations per hour, and capable of measuring 1/10th of a second, the El Primero became the technical foundation of the Maison’s identity.

At Watches and Wonders 2026, ZENITH unveils a new expression of this legacy: the CHRONOMASTER Sport Skeleton. Through its openworked architecture, the Manufacture reveals the mechanical complexity of its most emblematic calibre while introducing a new patented folding clasp, a new ergonomic development reflecting ZENITH’s holistic vision of performance, where movement engineering and functional innovation evolve together.

The CHRONOMASTER and the Living Legacy of the El Primero

The CHRONOMASTER collection carries forward the legacy of the El Primero, the world’s first automatic, integrated high-frequency chronograph calibre. From its inception, the movement distinguished itself by operating at 5Hz, or 36 000 vibrations per hour, a frequency that set it apart in the landscape of mechanical chronographs and established high-frequency precision as a defining element of ZENITH’s watchmaking identity. Over the decades, this architecture has evolved while remaining faithful to its original principle: enhancing chronometric stability and precision through elevated frequency.

Today, the CHRONOMASTER Sport continues this lineage with the El Primero 3600, regulated at 5Hz. This elevated frequency enables the precise measurement of 1/10th of a second as a direct mechanical consequence of its architecture. Unlike conventional chronographs, where the central chronograph seconds hand completes one rotation per minute, the El Primero 3600 drives a hand that circles the dial every 10 seconds. Each increment corresponds precisely to one tenth of a second and is read directly against the 10-second graduated ceramic bezel, making high-frequency performance both measurable and visible. This technical approach has consistently defined ZENITH’s chronographs for more than half a century.

A Transparent Architecture of Performance

With the CHRONOMASTER Sport Skeleton, ZENITH pushes this mechanical expression further by bringing the movement to the forefront.

The sapphire dial subtly tinted from black at the periphery to transparent at its center, reveals the openworked architecture of the calibre beneath. The skeletonization has been executed with careful attention to structural integrity and chronometric performance, ensuring that the movement’s high-frequency precision remains uncompromised.

The signature tri-colour overlapping counters, grey, anthracite and blue, remain an unmistakable reference to the original El Primero of 1969. Baton-style applied markers and faceted hands coated with C1 Super-LumiNova guarantee optimal legibility, preserving the functional clarity that defines the CHRONOMASTER collection.

Visible through both the sapphire dial and caseback, the El Primero 3600SK reveals its column wheel, finished in blue, and its horizontal clutch architecture. The movement incorporates a silicon escape wheel to enhance precision and durability, as well as a stop-second mechanism for accurate time-setting. Despite its high-frequency operation, it delivers a power reserve of 60 hours. The openworked rotor, engraved with the ZENITH star, maximizes transparency while maintaining winding efficiency and mechanical balance.

The CHRONOMASTER Sport Skeleton is presented in a 41mm case distinguished by alternating brushed and polished surfaces, reinforcing its sporty yet refined character. The classic pump-style pushers preserve its chronograph lineage, while the scratch-resistant ceramic bezel, graduated over 10 seconds, ensures precise readability of the 1/10th of a second indication. Water resistance is guaranteed to 10 ATM.

The CHRONOMASTER Sport Skeleton is available in four distinct versions. Two stainless steel executions: one featuring a green ceramic bezel paired with grey-toned counters, and one with a black ceramic bezel combining with the signature grey, anthracite and blue tri-colour counters. Both are presented on a three-link stainless steel bracelet and include an additional rubber strap.

A third version is crafted in 18-carat rose gold, paired with a black ceramic bezel and fitted on a black rubber strap.

Completing the collection is an exclusive limited edition of 10 pieces in rose gold, matched with a gold bracelet and crowned by a bezel set with 50 baguette-cut diamonds.

The CHRONOMASTER Sport Skeleton is available at ZENITH boutiques, online and in-store, as well as through authorized retailers worldwide.

ZENCLASP™: A New Patented Folding Clasp by ZENITH

With the CHRONOMASTER Sport Skeleton in stainless steel, ZENITH introduces its newly patented folding clasp, ZENCLASP™, developed to enhance both security and everyday comfort. Defined by smooth, rounded lines, its ergonomic architecture ensures a natural fit on the wrist, while the integrated safety-lock system and micro-adjustment mechanism provide secure fastening and precise sizing.

The folding clasp is secured by a lift-up safety cover adorned with the ZENITH star. Engineered for intuitive and precise operation, its closing system is reinforced by ceramic ball components that ensure accurate locking and maintain the exact relative positioning of the internal elements over time.

Its user-friendly micro-adjustment mechanism allows the bracelet to be resized without tools and directly on the wrist, without removing the watch. Adjustments are made by lifting a secondary cover, enabling 2.5 mm increments that offer a total adjustment range of 10 mm This system allows the bracelet to adapt seamlessly to natural variations in wrist size throughout the day.

From a technical standpoint, the folding clasp comprises 41 components, including 10 ceramic balls that secure both the locking and positioning functions of the mechanism. Its development required three years, or 1 800 hours, of research, engineering, and optimization. The durability of each function has been validated through extensive real-life testing equivalent to more than 10 years of use, representing over 600 000 cumulative opening and closing cycles.

The folding clasp will be progressively introduced across additional models and references. Fully compatible, it can be adapted to all CHRONOMASTER Sport bracelets that were not originally equipped with it.

ZENITH: THE HEART OF WATCHMAKING

Founded in 1865 in Le Locle, Switzerland, ZENITH has been at the forefront of Swiss watchmaking for over 160 years, driven by a pioneering spirit and a relentless pursuit of precision. As the first vertically integrated Swiss watch manufacture, ZENITH has continuously revolutionized horology by developing and manufacturing in-house movements, most notably the El Primero, the world’s first automatic, integrated high-frequency chronograph calibre launched in 1969, renowned for its unparalleled precision and high-frequency performance.

ZENITH’s timepieces celebrate its dedication to innovation and exceptional craftsmanship. The CHRONOMASTER collection embodies the expression of mechanical excellence and watchmaking versatility, the DEFY showcases technical innovation and bold design, while the PILOT collection celebrates ZENITH’s storied aviation legacy with distinctive, adventure-ready timepieces. This unwavering commitment to precision has been recognized with an unparalleled 2,333 chronometry prizes, underscoring ZENITH’s enduring legacy of excellence. The Calibre 135, having won most of those prizes, went through a modern re-engineering integrating up-to-date technical solutions and materials. ZENITH decided to give it a new home in its newly introduced G.F.J collection.

Throughout its history, ZENITH timepieces have accompanied pioneers who dared to dream big and achieve the extraordinary: from Louis Blériot’s historic flight across the English Channel to Felix Baumgartner’s record-breaking stratospheric free-fall jump. This daring spirit continues to drive the Maison as it redefines the future of Swiss watchmaking. Celebrating over a century and a half of excellence, innovation, and purpose, ZENITH remains at the forefront of Swiss horology, empowering those who challenge conventions and strive for greatness.

From Le Locle to the world, from 1865 to now, ZENITH is the heart of watchmaking.