Not all images were able to load for printing. Please close the print window and try again. The Brellum Duobox 39 TC Moonphase Chronometer
The latest 39mm Duobox takes things a step further with a triple calendar, moonphase, 12-hour chronograph, and blue sunray dial.
Founded in 2016 by fourth-generation watchmaker Sébastien Muller, Swiss indie brand Brellum started out with the Duobox that packed a pair of box-shaped sapphire crystals: one over the dial and another on the caseback. This was a retro-inspired chronograph with a 41.8mm steel case, piston-style pushers, and a COSC-certified Valjoux 7750 movement. A year later, the racing-inspired Duobox Pandial Chronograph joined the collection, complete with a tachymeter bezel and telemeter scale. Things went more compact in 2024, when Brellum released the Duobox 39mm, and now we turn to the latest Duobox 39 TC Moonphase Chronometer, which has a fair bit more happening than the original.
A couple of years ago, Brellum brought the Duobox into a smaller 39mm case, pairing it with a La Joux-Perret column-wheel chronograph movement. Before the collection expanded with pink and ice-blue mother-of-pearl versions, Brellum introduced the more elaborate Duobox Triple Calendar Moonphase in the original 41.8mm case. Now, the Brellum Duobox 39 TC Moonphase Chronometer brings that triple calendar and moonphase display into a 39mm case, with a 12-hour chronograph.
The steel case comes with an exhibition caseback, measuring 39mm across and 48mm from lug to lug. Its total thickness is 15.2mm, although the case itself measures 11.7mm without the crystals. This case combines brushed and polished surfaces, with a polished bezel and piston-style chronograph pushers. Its domed sapphire crystals on both sides give the watch its typical Duobox profile. Water resistance is rated at 100 metres. The Duobox 39 TC Moonphase Chronometer comes with a steel bracelet and one handmade calf leather strap, available in black or brown.
The blue dial has a sunray finish and a multi-level construction, with diamond-cut numerals and hands, as already seen in larger models. You will spot the day and month displays at 12 o’clock, inside the 30-minute chronograph counter. For the date, look for one of the central hands pointing to a scale around the edge of the dial, while the 6 o’clock sub-dial combines the 12-hour chronograph counter with the moonphase display. The day/night indicator at 9 o’clock completes this layout. Simpler baton indexes might have given the dial a little more breathing room, but the Roman numerals suit the watch’s classic calendar-watch feel.
The Brellum Duobox 39 TC Moonphase Chronometer uses the BR-751 automatic chronometer, based on the Valjoux 7751 movement (the calendar version of the ubiquitous 7750). It is chronometer-certified by COSC, runs at 28,800 vibrations/hour, and has a 46-hour power reserve. Brellum has decorated it with Perlage, Geneva stripes, and blue screws, and added a 4N-coated rotor with a moon-inspired design. Each rotor is also individually numbered.
The Duobox 39 TC Moonphase Chronometer is limited to 46 pieces, and at CHF 3,600 (without VAT), it offers great value for a COSC-certified chronograph with a triple calendar and moonphase. Brellum produces no more than 299 watches a year, so this is again a small batch from a small independent brand, but one that packs much into a relatively compact case. For more information, please visit brellum.swiss.
