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.
