n 2003, Zenith introduced the Chronomaster Open with the aim of making the high frequency beating heart of its El Primero calibre as prominently visible as possible. It marked the first time in the history of watchmaking that a chronograph featured a partially open dial solely to reveal the regulating organ and escapement. The Chronomaster Open was instant hit, lauded for its daring design that is often imitated but never matched. For Zenith, the partially open dial has remained a prominent and coveted feature in many of its Chronomaster references for nearly 20 years.

With 2021’s introduction of the new and improved El Primero 3600 that boasts a 1/10th of a second chronograph function and improved efficiency, the time had come to adapt and incorporate the latest developments into the emblematic Chronomaster Open. More than a simple facelift, the new Chronomaster Open is imbued with the lines and attributes of the latest generation of the Chronomaster collection. Somewhere between the sleek sportiness of the Chronomaster Sport and the historically inspired Chronomaster Original for a modern distillation of the essential Zenith El Primero chronograph.

Revisiting the iconic tri-colour dial configuration that debuted with the iconic A386 in 1969 and which remains a distinctive and instantly recognizable El Primero design element, the latest iteration of the Chronomaster Open retains it entirely with a transparent twist. Instead of cutting out the small seconds counter at 9 o’clock entirely as was the case with the previous versions of the Chronomaster Open, the three counter colours are retained thanks to a hesalite crystal element that serves as a readable sub-dial while allowing a view of the silicon star-shaped escape wheel. The opening itself has also been reinterpreted, foregoing the former version’s applied “frame” and instead opting for circular openings with chamfered edges, revealing the movement with more straight bridges and a more contemporary grey tone.

Catering to the prevalent demand for watches with more modest proportions, the round case now measures 39.5mm wide compared to the previous 42mm model, with slimmer lugs and more pronounced polished bevels on the edges. The pump-style pushers now feature rounded tips for a more ergonomic touch. The steel bracelet option follows the contours and mixed polished and satin-brushed finishes of the case.

Visible through the sapphire display back, the El Primero 3604 1/10th of a second automatic chronograph movement is a modified version of the 3600 that debuted in the Chronomaster Sport, featuring an open base plate and bridges that allow for a clearer view of the high-frequency 5Hz escapement with lubricant-free silicon escape wheel and pallet lever. The automatic winding mechanism with an open star-shaped oscillating mass efficiently delivers a power reserve of 60 hours.

Available at all Zenith boutiques and authorized retailers around the world, the Chronomaster Open is available in steel with a white or black dial, delivered with either a steel bracelet or cordura-effect rubber strap. A rose gold version featuring a white dial with a blue cordura-effect rubber strap is also introduced in the new line, along with a boutique-exclusive edition in steel with a blue dial and steel bracelet.

TECHNICAL SPECIFICATIONS

• Key points: Automatic El Primero column-wheel chronograph able to measure and display 1/10th of a second. Opening revealing the legendary beating heart of the El Primero movement. Silicon escape-wheel and lever. Increased power reserve of 60 hours. Stop-second mechanism.
• Movement: El Primero 3604 automatic
• Frequency 36,000 VpH (5 Hz)
• Power reserve approx. 60 hours
• Functions : 1/10th of a second chronograph functions. Hours and minutes in the centre. Small seconds at 9 o’clock, Central chronograph hand that makes one turn in 10 seconds, 60-minute counter at 6 o’clock, 60-second counter at 3 o’clock
• Finishes: New star-shaped oscillating weight with satined finishings
• Material: Stainless Steel
• Water resistance: 10 ATM
• Case: 39.5mm
• Dial: Black matte with two different-coloured counters & a translucent polymer counter
• Hour markers: Rhodium-plated, faceted and coated with " SuperLuminova SLN C1
• Hands : Rhodium-plated, faceted and coated with " SuperLuminova SLN C1
• Bracelet & Buckle: Metal Bracelet with a double folding clasp
• Price $10,000 USD