
This trilogy comprises the A384, a tonneau-shaped panda-dial model, the A385, featuring the same case but with an original gradient brown dial (possibly the first of its kind) and the A386, the most classic of the three models, with a round case but also the watch that first showed the signature tri-colour sub-counters, something that has become a hallmark of Zenith. It is the most iconic model in the trilogy introduced in 1969, the three watches created by Zenith to feature its newly developed and innovative movement, the El Primero calibre, regarded as one of the earliest automatic chronograph movements. The name “A386” will certainly resonate in the mind of vintage watch lovers as one of the most emblematic models ever to be produced by the Le Locle-based manufacture. Here is the Zenith Chronomaster Original, the revamped 38mm El Primero and the successor to the A386 watch. Indeed, the classic 38mm, bezel-less Chronomaster is back, with more modern mechanics and a powerful vintage-inspired design.

But this slightly larger and more modern take on the El Primero wasn’t meant to be a replacement. This very watch was, however, discontinued when the attractive Chronomaster Sport was introduced earlier this year. So yes the color scheme is similar but the subdials functions are quite different.For long, the name Chronomaster has been associated at Zenith with an El Primero-powered (what else…) classic chronograph, without an external bezel, often with tri-colour sub-dials and available either in 42mm or in an even more desirable, historically relevant 38mm diameter, inspired by the legendary A386 model of 1969. The 3600 has the advantage of being able to measure more granular time units whereas the 400b can measure longer (though I can't see why one would need to use a chronograph to measure 12 hrs.). Each rotation around the dial by the center seconds is 10 seconds and the subdials measure running seconds, seconds elapsed and minutes elapsed up to 60. Subdials measure running seconds, minutes elapsed and hours elapsed up to 12 hrs. The 400b operates like a traditional Chronograph, with the center seconds hand rotating around the dial once every 60 seconds. So something to make sure you're aware of.the color aesthetics of the two references are similar ( particularly the 38mm versions) but the functions of the two movements are going to be different. I couldn't tell you how widespread it is.
