Most horology aficionados are familiar with the legendary “El Primero” caliber movement, those who aren’t might not be as passionate as they like to believe.


Image courtesy of: Zenith

With the addition of this new model to the line, it’s now possible to obtain a “Zenith El Primero Chronograph” in three distinct dials designs: completely closed, half-open, or now completely open! A trifecta chronicling the progression towards opening up and displaying this historic movement in full.


Image courtesy of: Zenith

The case for these watches can be had in either a 38 or 42mm size, made out of either stainless-steel or a two-tone version with the steel topped by an 18k rose gold bezel. Despite its skeletonized dial the case back is also transparent, in order to further observe the intricacies of this mechanical movement, with its oscillating weight adorned with a “Côtes de Genève” pattern and other moving parts.


Image courtesy of: Zenith

There are two push-pieces on the right-side of the case to operate the chronograph functions, with a crown in between them. The crown also features the classic embossed star logo on the top of it and a thin line was added to the heads of the piston style pushers. Overall the 38mm version may be closer to the original model it’s based on since they share the same diameter, but the 42mm has been crafted proportionately, so it all comes down to a question of personal taste or wrist size. Water-resistance on this watch can reach up to 100 meters (330 feet).


Image courtesy of: Zenith

Time is exhibited in this see-thru, aforementioned fully skeletonized dial with either: stainless-steel or 18k rose gold hour index markers, depending on the model opted for, accompanied by smaller minute index markers. Yet followed by even smaller minute index markers with Arabic numerals for every five-minute increment.  There are three sub-dials: a 30-minute counter at the 3 o’clock position; a 12-hour counter at the 6 o’clock position; and a sub-seconds at the 9 o’clock position. The hands and hour index markers have all undergone a luminescent coating, for an enhanced legibility. There is also a date aperture at the 6 o’clock position.


Image courtesy of: Zenith

Zenith Chronomaster Full Open

These “Zenith Chronomaster Full Open” (References below) are powered by a self-winding mechanical movement, caliber El Primero 400 with 31 jewels, 326 components and 36,000 Vph. Power reserve on this timepiece can last up to 50 hours, when fully wound. It’s the same iconic caliber movement that’s been in production since 1969, we find inside both these new timepieces.


Image courtesy of: Zenith

Mounted to these watches is either a: black or brown alligator leather strap with protective rubber lining, secured to the wrist by a stainless-steel triple folding clasp. For more up to date information visit the official Zenith official website here.

Ref#: 03.2153.400/78.C813 38mm steel

Ref#: 51.2151.400/78.C180 38mm steel with 18k pink gold bezel

Ref#: 03.2081.400/78.C813 42mm steel

Ref#: 51.2081.400/78.C810 42mm steel and 18k pink gold bezel


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Zenith, Chronometer, Full Open, El Primero, Luxury Watches

Written by Mauro Az