Zenith revolutionised the watchmaking industry back in 1969 by debuting the very first automatic chronograph movement. This was the birth of the El Primero, and it is astonishing thaat this name lives on today, nearly 60 years later. Something that almost always gets lost to the annals of history is the fact that not only was the El Primero the first automatic chronograph ever, it was also the first movement of its kind to achieve a high beat rate of 36,000 vph or 5 Hz. Of course, today, most chronograph movements are automatic winding by default, but still, not many are able to offer a frequency of 5 Hz; most hover around the 3 to 4 Hz mark. This became one of the technical foundations of the maison and remains one of the legacies of the Zenith El Primero movement.

Generally, the reason for a higher oscillation rate is to improve chronometric precision. The idea here is that if the oscillator vibrates at a higher rate, it cancels out the micro-variations of its oscillations. Also, higher speeds mean higher angular momentum, making it more stable when a watch changes positions or even recovers faster when the regulating organ receives shocks. For a chronograph, however, one of the added bonuses for a 36,000 vph movement is that the timing precision can be measured to 1/10th of a second. Because if you do the math, 36,000 vibrations per hour means 600 vibrations per minute and 10 vibrations per second. And to make this even easier to read, the Chronomaster Sport has a chronograph seconds hand that makes one full rotation of the dial in 10 seconds rather than the usual 60, so that the 1/10th of a second can be read instantaneously on the bezel when the chronograph is stopped. It is a very subtle detail, but if you notice, on the ceramic bezel, it reads 1/10th of a second instead of a tachymetre that is found on most chronographs of this style.

For 2026, Zenith has decided to reveal more of the technical mastery that allows this to happen by skeletonising the movement and combining it with a transparent dial. The El Primero 3600 SK movement was delicately openworked with careful attention to structural integrity and chronometric performance, ensuring that the movement’s high-frequency precision remains uncompromised. And as an added level of sophistication, the sapphire dial is subtly tinted from black at the periphery to transparent at the centre. The signature elements that define an El Primero chronograph—the grey, anthracite and blue subdials—have also been cleverly retained despite the transparent nature of the dial.

What is perhaps the most overlooked aspect of this new Chronomaster Sport Skeleton is the clasp on the bracelet. Yes, you read correctly. This clasp is a completely new patented folding clasp for the watch and took them three years, or 1,800 hours, of research to develop. The clasp is secured by a liftup cover and a fastening system reinforced by ceramic ball components. There is a new micro-adjust function on the watch that allows for 2 mm increments across five positions—a total range of 10 mm—without the need for tools, and lastly, it has been tested for use in simulations exceeding 10 years, which is more than 600,000 cumulative cycles.