The El Primero Striking 10^th chronograph embodies the grand return of the Manufacture Zenith to the technical values that have forged the brand’s success. Unequalled to date, the legendary El Primero calibre was the world’s first automatic chronograph to beat at a rate of 10 vibrations per second. It is the most sophisticated mechanical ‘motor’ and the one boasting the highest degree of precision, since the vast majority of other mechanical movements beat at 8 vibrations per second at best. The model presented at Baselworld embodies a major horological breakthrough by showcasing tenths of a second, meaning each pulsation of this exceptional mechanism. This development represents a considerable advancement in the principle of jumping or flying seconds. Now for a closer look at this significant return to genuine watchmaking values.

The higher the balance’s frequency of oscillation – easily perceptible by the speed of the ticking – the higher the quality factor determining the accuracy of the movement. The El Primero calibre developed in 1969 opted for a cadence of 10 vibrations per second, a rate that still represents one of the greatest horological challenges, since other calibres generally reach a maximum of 8 vibrations per second.


The El Primero Striking 10^th renders each pulsation of its motor clearly visible. Directly connected to the regulating organ, each jump of the central chronograph hand marks a 1/10^th of a second, the smallest division of time measured by a series-produced mechanical calibre. While measuring such a short fraction of time is a genuine accomplishment in itself, making it perfectly readable is yet another. To achieve this, Zenith has considerably refined and improved the principle of jumping seconds. The chronograph hand makes a complete dial rotation in 10 seconds and each of its steps precisely indicates a 1/10^th of a second against the 100 graduations engraved on the dial. It is worth nothing that, for the user of this chronograph, the 1/10^th of a second is a natural unit of the decimal system, whereas the 1/8^th or 1/5^th of a second shown by so-called classic jumping seconds hands are far harder to perceive. With this model, Zenith is clearly reasserting its brand territory, meaning that of pure timekeeping performance.

This chronograph exudes admirable presence on the wrist. The perfectly balanced case accentuates the resolutely masculine nature of this model. The three subdials consisting of the two chronograph totalizers and the running seconds display are arranged in a V shape on the lower part of the dial. The perfect readability of the measured time is guaranteed by three different shades on the subdials. The five-pointed star shines at the ‘zenith’ of this timepiece which achieves the considerable technical feat of rendering each beat of its exceptional movement clearly visible.


Making an El Primero movement involves:
a symbolic nine months of work during which 20 watchmakers play successive roles in developing and crafting this movement
no less than 5’500 operations
50 milling operations of various dimensions on the dial side
77 other milling operations on the bridge side
5 and 50 operations for each part
18 different metals in its classic version
The heart of the El Primero beats at a rate of 36’000 vibrations per hour, meaning 864’000 a day or 315’360’000 beats per year
one vibration corresponds to the position of the lever as it swings to and fro, making the alternating “tick” and “tock” sounds. As there are 3’600 seconds in an hour (60 seconds times 60 minutes), and since El Primero beats at a frequency of 36’000 vibrations per hour, the hands actually thus make 10 jumps per second, thereby marking off tenths of a second.

The jumping seconds chronograph reinvented by Zenith is distinguished by a chronograph hand completing its rotation in just 10 seconds and thereby considerably improving the 1/10^th of a second read-off. This significant new feature is backed by six-times larger divisions on the outer dial ring (10 seconds instead of 60) enabling totally accurate readings to within 1/10^th of second. One particularly important feature of this model lies in the chronograph stop function. When it is stopped, the hand-locking system brings the hand to an extremely precise halt, since the brake-lever positions the hand between two of the 100 teeth on the chronograph wheel, thereby further enhancing the precision of the 1/10^th of a second read-off. The original El Primero movement sweeps around the dial in 60 seconds in tiny 1/10^th of a second jumps, meaning the chronograph hand performs 600 jumps a minute. In this new jumping seconds model, the ultra-fast stopping and restarting of this large chronograph hand 10 times a second calls for a greater amount of energy. The watch functions had to be significantly improved and optimised to enable this energy-consuming acceleration. Seeking to reduce the energy required naturally entailed making the movement wheels as light as possible, which is why some of them are in silicon – a material three and a half times lighter than its traditional counterparts.


Driven by the El Primero 4052 B automatic calibre, the new El Primero Striking 10^th chronograph comes in a choice of 18-carat rose gold or stainless steel for its 42 mm case that is water-resistant to 10 ATM (100 metres) and fitted with a sapphire crystal glareproofed on both sides.

The silver sunray-brushed dial features circular satin-brushed zones for the rose gold version. Both the stainless steel model and the gold model feature three counters. On the stainless steel version, these come in subtle shades of blue and grey, while the rose gold version features three anthracite counters. The faceted hands and hour-markers coated with Superluminova are rhodium-plated, or gold-plated on the rose gold models.

The distinctive 1/10^th of a second indication is clearly marked off by the dedicated chronograph hand.

This elegantly sophisticated model is fitted with a rubber-lined black alligator leather strap, secured to the wrist by a pin buckle in stainless steel or 18-carat rose gold, or by a stainless steel bracelet with triple folding clasp. Vividly embodying a revolutionary technical enhancement that is reflected in its stand-out design, the El Primero Striking 10^th chronograph takes high-precision timing read-off to a whole new level.