I’ve had the opportunity to review several different watches from Brellum over the course of the past couple of years, and while I’ve consistently been impressed by the brand’s offerings, its chronographs are right at the upper size limit for what I can comfortably wear on my fairly narrow wrist. Brellum always does a commendable job of mitigating what might otherwise be rather large dimensions, although carefully considered proportions have limits in terms of how much they can visually shrink a design, and the brand’s full-size chronographs are simply too large for some collectors. For its latest release of 2024, Brellum has created a new smaller chronograph, and the Brellum Duobox 39 Chronometer takes the fundamental concept of its signature Duobox series and renders it in a compact sub-40mm package.

At the time of launch, Brellum is offering its new Duobox 39 Chronometer in three different colorways (blue, silver, and anthracite), and each will be produced as a limited edition of 46 examples. For those who may not be familiar with Brellum, the small-scale independent Swiss brand has a total output of just 299 watches per year, and all of its timepieces are COSC-certified chronometers. While 46 examples of each colorway (138 watches total) might sound like an incredibly small production run, this ultimately accounts for nearly half of Brellum’s annual output, and other limited-edition models, such as the brand’s Duobox Triple Calendar Moonphase and Pandial Marina Bicompax Titanium have been produced in similarly small numbers. With that in mind, while Brellum’s previous limited-edition chronographs have all been based on the same fundamental middle case, the new Duobox 39 Chronometer represents a tangibly different offering that is noticeably more compact in all its key dimensions.

Crafted from 316L stainless steel with satin-finished surfaces and high-polished accents, the case of the Brellum Duobox 39 Chronometer features a similar overall design to what can be observed on the brand’s full-size Duobox models, along with its various limited-edition pilot watches like the Pilot LE.2 GMT. With that in mind, the Duobox 39 Chronometer is significantly smaller, and its case measures 39.5mm in diameter, with a 39mm bezel further reducing the visual profile of the watch. Additionally, Brellum’s new smaller chronograph features a slightly narrower 21mm lug width, while its lug-to-lug distance has been reduced to 48mm, and it is also slightly thinner, with a total height of 15.3mm. While this still might sound like a properly chunky timepiece, only 11.05mm of that total thickness comes from its stainless steel case components, and the rest of that on-paper 15.3mm dimension is occupied by the domed sapphire crystals (with anti-reflective treatment) that are fitted to either side of the watch.

Despite being smaller than its full-size chronograph siblings, the new Brellum Duobox 39 Chronometer still isn’t an especially thin timepiece, and with a weight of approximately 76 grams (not including its strap or bracelet), it ultimately offers a solid amount of wrist presence. However, just like Brellum’s full-size chronographs, the Duobox 39 Chronometer wears its height incredibly well, and its carefully considered case architecture mitigates what might otherwise be a rather imposing profile. Since nearly a third of its overall thickness is occupied by the pair of domed sapphire crystals that are fitted to its bezel and caseback, the Duobox 39 immediately appears smaller than a similarly sized watch with a slab-sided design, and its downward curving lugs and domed caseback further help the watch sit low against the wrist.

The minor reduction in case thickness is certainly welcome, although the smaller diameter and shorter lug-to-lug distance are far more significant, and they result in the Brellum Duobox 39 Chronometer having a noticeably more compact overall profile. Aside from its reduced dimensions, the rest of the Duobox 39 Chronometer’s exterior follows in the footsteps of its larger siblings, and its caseback is secured by a set of six small screws, while a signed crown and pair of pump-style chronograph pushers protrude from the right-hand side of the case. Additionally, while neither the crown nor pushers screw down to the middle case, the Duobox 39 Chronometer still offers a depth rating of 100 meters, which is the same amount of water resistance that can be found among Brellum’s larger chronograph models.

While Brellum’s full-size Duobox models have dials with a 6-9-12 register layout, the new Duobox 39 Chronometer opts for a more traditional 3-6-9 orientation, with a rectangular date window neatly set within the recessed sub-dial at 6 o’clock. Applied hour markers and raised rings for the chronograph registers provide the dial with additional depth, and small colorful accents punctuate the minute totalizer and central chronograph seconds hand. While the anthracite version featured here receives bright green highlights, the blue model has these same details in orange, and the silver-dial Duobox 39 Chronometer has red accents on its dial paired with a bright blue central chronograph hand. Additionally, while the anthracite-dial prototype photographed for this article has a standard black calendar disc, the production models will have date discs that are color-matched to the surface of their dials.

Printed along the outermost perimeter of the Brellum Duobox 39 Chronometer’s dial is a pulsations scale; however, the curvature of the domed sapphire crystal almost entirely obscures it from view when looking directly at the watch, and you have to tilt the case at an angle before you can clearly see the scale’s numerals. Small dots of Super-LumiNova are added to the ends of the polished hour markers, while the pair of time-telling hands receive luminous inlays running down their centers, and all of the Super-LumiNova used on the Duobox 39 Chronometer emits a blue-colored glow in the dark. Due to the relatively small size of its luminous elements, the Brellum Duobox 39 Chronometer’s lume performance is fairly average, although it undeniably helps aid with low-light legibility, and the modestly sized luminous plots allow the dial to maintain a rather refined and elegant overall appearance.

Unlike Brellum’s various full-size chronographs that run on Valjoux-based calibers, the new Duobox 39 Chronometer is powered by the brand’s Cal. BR-110 automatic chronograph movement based upon the architecture of the La Joux-Perret Cal. L110. Rather than having a cam-operated system, the Cal. L110 uses a column wheel to control its chronograph complication, and the column wheel component has been given a bright blue finish that matches the blued screws that secure the movement’s plates and bridges. Running at a frequency of 28,800vph (4 Hz) with a power reserve of approximately 60 hours, the 26-jewel Brellum Cal. BR-110 is a COSC-certified chronometer, which means that it guarantees an accuracy rating of -4/+6 seconds per day, and the BR-110 movements fitted to the trio of Brellum Duobox 39 Chronometer models receive custom 4N gold-plated rotors that are engraved with each watch’s limited-edition number out of 46 examples.

Regardless of dial color, all three versions of the Brellum Duobox 39 Chronometer come as a set with both a stainless steel bracelet and a black veal leather strap. The strap appears to be more-or-less identical to what can be found on other Brellum models (such as the previously mentioned Duobox Triple Calendar Moonphase), and it features a crocodile pattern on its outer surface with a stainless steel deployant clasp. Meanwhile, the bracelet features a rounded five-link design with brushed sides and high-polished centers, and although it consists entirely of solid machined components, it uses a pin-and-collar setup for its removable links, rather than the more premium approach of single-sided screws. The bracelet for the clasp adheres to a traditional butterfly-style design with perlage adorning the inner folding section, and while it doesn’t offer any form of integrated micro-adjustment system, Brellum does include two half-links to help owners achieve m a more custom-tailored fit on the wrist.

The bracelet for the Brellum Duobox 39 Chronometer tapers from 21mm at the case down to 19mm on the underside of the wrist; however, given that its lug width is already somewhat large relative to its 39mm diameter, I personally would have preferred for the bracelet to have an additional couple millimeters of taper to better accentuate the reduced proportions of the case. For someone like myself with wrists in the range of 6.5 to 6.75 inches, the bracelet may feel slightly too wide for the watch, although individuals with larger wrists will likely be happy to have the extra bracelet width, as it will allow them to enjoy the comfort of a compact case profile without having a watch that feels too small or dainty. Given that the Duobox 39 Chronometer comes as a set with both a strap and bracelet, an integrated quick-release system would have been a welcome addition, although this is a truly minor nitpick, as even the most novice of collectors are capable of using a springbar tool to change a strap.

In terms of its overall design, execution, and attention to detail, the new Duobox 39 Chronometer very much feels like a Brellum chronograph, although its reduced dimensions provide the model with a significantly different, almost vintage-leaning spirit compared to what exists among its larger siblings. While all three colorways of the Duobox 39 Chronometer are limited editions of 46 examples, I wouldn’t be surprised to see this reduced-size format adapted to other models at some point in the future, similar to how Brellum has created multiple different executions of its full-size chronographs. With an official retail price of $3,690 USD, the Brellum Duobox 39 Chronometer is positioned right in the same neighborhood as similar models from the brand’s current lineup, and it serves as an ideal alternative for anyone who has been eyeing Brellum’s chronographs but was previously deterred by their size. For more information on the Brellum Duobox 39 Chronometer, please visit the brand’s website.