Review: The Isotope GMT 0º

I sometimes wonder if people in my life are taken aback by how much I ramble on about my love for travel watches. I think it’s because those who know me best understand that I don’t actually like to travel. Don’t get me wrong, I very much enjoy “being on vacation” and experiencing places that are new to me, but the actual “travel” part has always felt like kind of a drag, something that has to be endured. I am not, for example, one of those people who simply can’t wait to jump on a plane again once the pandemic is over, and/or vaccines make it reasonably safe to fly again. I mean, I will get on a plane again. Of course I will. But the travel “bug” that some people claim to be infected by is not something I’ve caught. I like home just fine. 

That feels like a surprisingly controversial statement, and might come as a surprise to those who I’ve no doubt bored to tears in talking up the benefits of a jumping local hour GMT versus the far less efficient “caller” variety. For my purposes, the caller GMT that allows for independent adjustment of the 24 hour hand is actually perfectly appropriate almost all of the time, particularly under a virtual Covid-19 house arrest. These watches for me are more about mechanical ingenuity, aesthetics, and a romantic link to a time long past than any actual practicality in my everyday life. Such is the case with so many watches, and so many of the rabbit holes we jump down as enthusiasts. 

That brings me to the Isotope GMT 0º, which is designed unlike any GMT watch I’ve seen before, but has the familiar caller functionality I’ve often dismissed. This watch, though, is playing with a genuinely interesting design language, and if there’s one thing I love more than a GMT watch, it’s a watch that brandishes a new and bold style. That’ll get you pretty far in my book, even if some of the big and bold swings that are taken in the design department result in a whiff. 

We should note here that the review samples Isotope provided are prototypes, so some of the issues here will be corrected in the final production version. Even in prototype stage, however, it’s easy enough to get a sense of the fairly dramatic departures the brand has taken from a traditional GMT format. 


Review: The Isotope GMT 0º

Stainless steel
Swisstech S24-45
White, blue
Yes, on hands
Water Resistance
200 meters
41.5 x 48mm
Lug Width
Screw down


A quick glance at the GMT 0º’s dial reveals that a quick glance simply won’t do. This is a dial that has a learning curve, which may or may not be a dealbreaker right off the bat. For some, it’s surely part of the charm, and those folks will be well rewarded by getting up close to Isotope’s novel design. 

The most prominent differentiating feature of the GMT 0º is the rotating disc at the dial’s center. This effectively replaces a GMT hand, making a full rotation around the dial in a 24 hour period. A tear shaped indicator points to the correct hour, which is read off a track immediately outside the spinning disc. This “lacrima” shape is important to Isotope’s branding and appears throughout their watches – it’s repeated on the GMT 0º, with the upper portion of the hours track bulging out to mimic the shape of the marker. 

Outside the 24 hour scale you’ll notice a series of 31 holes through which the date is displayed by a roving colored circle that fills in a hole that corresponds to the correct date. It’s a pointer date without the pointing. Unfortunately, on these prototypes this function was mostly theoretical –  the date indicator is very difficult to see. It simply doesn’t create a distinct enough contrast with the surrounding colors, and often, as I was wearing the watch, the date was a mystery. Of course, this is often the case with me anyway, as I frequently forget to set the date on my watches that are so equipped. But at least in those instances I’m armed with misplaced confidence.

The local time is read the traditional way with long and thin hour and minute hands that point to hour markers that are cut into the dial’s top layer, further emphasizing the GMT 0º’s sandwich effect. The tips of these hands are lumed (as is the 24 hour indicator) but the body of each hand is skeletonized. On the white dialed watch, I found it somewhat difficult to find the hands when quickly checking the time. It’s less of a problem on the blue dialed variant because the lumed portion of the hands contrasts well with the dial’s base color. 

In spite of the mass of information that can be read off the dial, it has an expansive quality to it that I like in the abstract, but in practice likely contributes to it being somewhat difficult to read. More than most dials, I found myself having to squint to actually read numerical information (on the 24 hour scale) or find the hands and date indicator – a lot of the stuff you need to look at to take full advantage of this watch’s complications is incredibly small. Additional contrast would really help, but Isotope would likely lose the open feeling they’re reaching for, and ultimately achieve. This is far less of a problem on the blue dial than the white, but both have numerical text that is so tiny I imagine only the most eagle eyed will be able to read it quickly. This watch illustrates just how much contrasting colors have positively impacted my ability to read dial information on any number of watches that I’ve handled in the past. 


The GMT 0º has a big, chunky case, but wears reasonably well for a watch of its size. It measures 41.5mm in diameter, but the figures that most directly illustrate this watch’s proportions are its height (14.2mm) and lug width (24mm). It’s a tall watch, but a gently sloped bezel saves it from hockey puck status. It has a generous heft yet feels well balanced for the most part, but I’m a large wristed guy and can easily wear watches up to 44mm, even if my strong preference is for watches that are quite a bit smaller. The lugs are very short, and keep the total lug to lug span a manageable 48mm, according to my calipers. 

My bet is that a reason for the GMT 0º’s large and in charge dimensions has a lot to do with its 200 meter water resistance rating. Now, I’m all for tool watches and divers that rack up impressive specs for the sake of impressive specs. That’s part of the culture of this hobby, and it often leads to some really satisfying and impressive watches. But this watch seems like a casualty of the growing expectation that for a watch to have credibility as a tool, it must have at least 200 meters of water resistance and a screw down crown. The GMT 0º would likely pass any reasonable robustness test you put in front of it, but I wonder why it needs to, and can’t help but think the whole package would be a lot more appealing in a thinner case with 100 meters (or less!) water resistance, with a footprint that would perhaps feel a bit more wearable. While it’s true that this would generate comments from anonymous Instagram keyboard warriors begging to know how anyone could live with a mere 50 meters of water resistance (the horror!), I think a well sized, sleek watch with a truly interesting dial would find its audience. That dial, after all, doesn’t read as a traditional sports watch design anyway given the effort required to learn it, so it’s a bit puzzling to me why Isotope decided to build the GMT 0º with full fledged tool watch specs.

A tenet of criticism of any kind is to evaluate how effective something is at what it sets out to do, and not to fault it for lacking characteristics of a thing its creator never intended to pursue, so I don’t wish to fall too far down the trap of wishing the GMT 0º was a type of watch that Isotope simply had no interest in creating. But I do think that in general it’s well worth it for brands to closely examine the trade-offs of things like water resistance versus thickness, and consider that, despite what you see in Instagram comments these days, it’s actually perfectly acceptable for a watch design to place a higher value on wearability and comfort than pure specs, and that as long as you’re using decent gaskets, virtually any modern watch can handle scrubbing dishes, or getting caught in the rain, which for many of us is the extent to which we expose our watches to moisture on any regular basis. 

A nice design forward feature of the case that I unequivocally enjoy is the subtle accent on the outside of each lug. Small trapezoidal shapes are etched into the lugs, seemingly for no other reason than because it looks cool. Well, it does look cool, and made me immediately think of the injection molded lugs on Galli S1 Timex that we covered recently, but at a much smaller and more subtle scale. The case flanks have a very subtle protrusion outward that is a literal mirror of the lug accents, and also recalls the slightly askew lacrima design that’s repeated multiple times on the dial. There’s a cohesiveness between the case and dial design that’s quite satisfying on the GMT 0º.

Straps and Wearability 

Earlier in this review I mentioned the somewhat unusual lug width of 24mm, and if you thought I was just going to glide by that and not return, you’d be mistaken. This watch has a wide stance, but it’s not uncomfortable or difficult to wear. With a 24mm lug width, you really notice the additional wrist real estate that gets taken up at the top and bottom of the watch, and I would imagine this would impact someone with a small wrist to a much greater extent than it did for me. Visually, I’m not a fan of how it looks, but in terms of wrist feel, I don’t have major complaints. Because the lugs are somewhat short, the GMT 0º doesn’t feel out of proportion to me, but this watch could easily get out of control if the lugs were long and thin, like those of a traditional skin diver, for example. The fact that the GMT 0º feels like it’s made up mostly of its case, almost like a Seiko Tuna or Monster, is definitely to its benefit. 

One of the strangest things about this watch is the aesthetic impression left by the strap and tang buckle. It’s relatively common for wider straps not to taper very dramatically – this leads to a floppiness or instability with larger watches. The straps on the GMT 0º are no exception and don’t have a taper at all, and the top half terminates in what has to be the most massive tang buckle I’ve ever seen. I’m unsure if this is something Isotope plans to change in the regular production version of this watch, but my hope is that they do, as it’s quite simply a miss in almost every regard. While the buckle itself is well machined, its size diminishes the key benefit of a tang style attachment to nil. That is to say, its presence is felt at every moment while on the wrist, and I felt the same annoyance with Isotope’s tang as I have with many ill conceived deployant clasps. Needless to say, if I owned this watch, the strap would be immediately swapped, likely for a NATO of some kind. Unfortunately, that exchange would require the use of an additional tool, as the spring bars are attached with screws. I know that the Panerai faithful love this style of spring bar attachment, and I can appreciate the benefits when it comes to reliably keeping the spring bar attached to the case. I think I’m just disappointed that my ninja-like spring bar tool skills are wasted here, but that’s admittedly a personal problem that I’ll have to grapple with. 


Isotope is using the Swisstech S24-45 movement in the GMT 0º, which has effectively the same functionality of equivalent movements from Sellita and ETA. Operation is straightforward – pulling the crown out to first position enables date setting when rotated in one direction, and setting of the 24 hour disc in the other. Pulling the crown out to the next position hacks the movement and allows for setting of local time. The movement is partially visible through the caseback, which is solid except for a lacrima shaped cutout at the center, which reveals the inside of the winding rotor with Isotope branding. The world’s time zones have also been arranged in a circular pattern on the caseback, which is a helpful reference should you need to quickly calculate GMT offset for a given part of the world. 


Isotope wasn’t a brand I was familiar with prior to my exposure to the GMT 0º, and while I clearly think this particular watch has some issues that should be worked out before the final production version is ready, I think the overarching dial design has real promise. The idea of illustrating vital dial information via a series of dots that shift around the dial is a good one, and we’ve seen similar executions from Ochs und Junior, which I imagine was an influence on Isotope to some degree. But the GMT execution specifically, and the way it plays with shape, is more unique, and if Isotope can get the colors just right to provide the right contrast, I can see the whole package falling into place very nicely. It’s clear that a great deal of care has gone into communicating something very specific with the intentionality of the dial and case design, and that kind of dedication and thought is always worth paying attention to in our segment of the watch industry, when it seems to that too many brands cut corners, take the easy way out, or have not much to say at all. Even if something ultimately doesn’t work, there’s value in the effort and attitude that goes into creating it in the first place, and I look forward to seeing what else Isotope comes up with in the future. 

The GMT 0º is currently available for pre-order from Isotope at a cost of $982.27. There are a total of six variants available, including limited editions with red and green dials (and a black DLC coating on the latter). Delivery is expected in June, and Isotope expects to make improvements to the final versions of the watches not just in legibility of the dot indicators on the dial, but also in lug finishing, and the quality of the cordura strap that is offered. More information can be found at Isotope’s website here.

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Zach is a native of New Hampshire, and he has been interested in watches since the age of 13, when he walked into Macy’s and bought a gaudy, quartz, two-tone Citizen chronograph with his hard earned Bar Mitzvah money. It was lost in a move years ago, but he continues to hunt for a similar piece on eBay. Zach loves a wide variety of watches, but leans toward classic designs and proportions that have stood the test of time. He is currently obsessed with Grand Seiko.