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Zenith - El Primero Chronomaster Open Power Reserve

Zenith El Primero Chronomaster Open Power Reserve

This Zenith model uncovers the very essence of time and reveals, in the openings on its dial, the 36,000 vibrations of its movement: the legendary El Primero.

Press Release

The Chronomaster Open unites in a spectacular fashion the most rigorous watchmaking tradition with bold contemporary design. This Zenith model uncovers the very essence of time and reveals, in the openings on its dial, the 36,000 vibrations of its movement: the legendary El Primero. The aperture invites interest as much by the magic it emanates as by the curiosity it inspires. But make no mistake: the Chronomaster Open is first and foremost an example of technological prowess, a timepiece that is 100% technical and 100% passion.

El Primero Chronomaster Open Power Reserve, Rose Gold 18 carats, 
silver dial and  brown alligator-skin strap © Zenith



The Chronomaster Open model leaves no-one indifferent. The open dial – a Zenithcreation – lets one see into the perfectly synchronized pulsations and the magic of the mechanism in what is today unanimously considered as the “best serial movement in the world” for its performance and its chronometric reliability. Its secret lies in its number of vibrations, which is 25% higher than in other movements on the market. Whereas other timepieces make 8 vibrations per second, the El Primero caliber makes 10 in the same time. Over and above the aesthetic success of this open-heart operation – the Open concept is the realization of technical prowess: to make the regulating organ visible, it has been moved to 10 o'clock, on the edge of the movement. 

El Primero Chronomaster Open Power Reserve, steel case, 
black sun-burst dial and  black alligator-skin strap © Zenith

The great watchmaking tradition
Everything here evokes the great tradition of watchmaking: a column-wheel chronograph mechanism; a power reserve indicator; a rhodium-plated plate, circular- graining and chamfered bridges; strokes drawn on the hammers, levers and conveyors; oscillating weight with “Côtes de Genève” guilloché work; revelation of the Zenith star through skeleton work and tachometric scale on the flanges that harks back to the chronographs used in the first automobile races. One can only admire the attention to detail.




Aesthetic daring
The Chronomaster Open displays an avant-garde design with highly finished features. This aspect is important in the choice of a watch, one of the only pieces of jewelry worn by men, an accessory that identifies and highlights his personality. Zenith communicates the image of a highly technical brand that is intended for connoisseurs of high-precision watchmaking.


Using the design codes of the past to interpret contemporary models, the Chronomaster Open is based on a century and a half of watchmaking expertise. The Open model exists in four different versions: a silver or black sun-burst dial in a steel case or silver sun-burst dial in an 18-carat rose gold case or in a rose gold and steel case. The markers and the three hands for the hours, minutes and small seconds are facetted, rhodium-plated, and hand-set. The central hand of the chronograph, the hand for the 30-minute counter and for the power reserve have a blued finish. The curve of the hands that decorate the dial is executed with precise handwork. The Chronomaster Open model belongs to Zenith'S “Iconic” family.



Movement El Primero 4021P, Automatic © Zenith

El Primero chronomaster Open Power Reserve-The emblematic feature of the OPEN model is the revealing of the heart of the legendary EL PRIMERO movement
-Automatic chronograph with column wheel and power reserve indicator
-Movement with 36,000 vibrations/hour, developed and manufactured in-house for over 40 yearsTechnical dataMovement:
El Primero 4021P, Automatic
Caliber: 13 1/4 ``` (Diameter: 30 mm)
Height: 7.85 mm
Parts: 248
Jewels: 39
Frequency: 36,000 V/h – (5 Hz)
Power reserve: approximately 50h
- Regulator assembly with fine adjustment
- Central rotor on ball bearings
- Automatic winding in both directions
- Rapid date reset
- Chronograph function
- Chronograph control center via column wheel
- Rhodium-plated platinum
- “Côtes de Genève” or circular graining and chamfering on the bridges
- Strokes drawn on the hammers, levers and conveyors

Oscillating weight:
Metal oscillating weight with guilloché work in a “Côtes de Genève” motif and revelation of the ZENITH star through skeleton work
- Central hours and minutes
- Small seconds at 9 o'clock
- Second chronograph counter in the center
- 30-minute counter at 3 o'clock
- Power-reserve indicator in the center
Diameter: 42 mm
Crystal: Sapphire glass treated with anti-reflection on both sides
Case back: Transparent sapphire glass
Water resistance: 10 ATM / 100 meters
Available models:
Available in steel, 18-carat two-toned or rose gold with silver or black sun-burst dial and a brown or black alligator-skin strap 



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