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.
A New Patented Folding Clasp by ZENITH
With the CHRONOMASTER Sport Skeleton in steel, ZENITH introduces a new patented folding clasp. Defined by smooth, rounded lines, its ergonomic design delivers exceptional comfort on the wrist, while its safety-lock buckle and micro-adjustment system ensure both secure wear and a precise fit.
The folding clasp is secured by a safety lift-up cover emblazoned with the ZENITH star logo. Its construction enables straightforward and precise operation, with secure fastening reinforced by ceramic ball components.
Its user-friendly micro-adjustment mechanism allows the bracelet to be resized without tools, enhancing everyday comfort. The bracelet can even be extended directly on the wrist without removing the watch. Micro-adjustments are made by lifting a secondary cover, enabling 2 mm increments across five positions — for a total adjustment range of 10 mm.
From a technical standpoint, the folding clasp consists of 41 components, including four double-ball pawls and two single-ball pawls. Its development required three years — or 1,800 hours — of research, fine-tuning and optimization. Durability has been validated through simulations exceeding 10 years of use, representing more than 600,000 cumulative cycles.
The folding clasp will be progressively deployed across additional models and references. Fully compatible, it can be adapted to all CHRONOMASTER Sport bracelets that were not originally equipped with it.
