With the new Square Bang Tourbillon 4-Day Power Reserve, Hublot introduces no fewer than four firsts within the collection: a case made entirely of 3D carbon, the omission of a chronograph function, the first tourbillon, and a fully square-constructed movement.
When it was launched in 2022, the Square Bang collection introduced a bold new design language to the Big Bang family, bringing with it a square case as a more assertive alternative. With the Square Bang Tourbillon 4-Day Power Reserve, Hublot now adds a technically ambitious model to the line – one that, for the first time, combines a case made entirely from 3D carbon with a skeletonised dial and the first square-shaped movement of the collection. It also marks the debut of a tourbillon in the Square Bang series and is the first to forego a chronograph in favour of two central hands alone. Let’s take a closer look at the construction and design of the new Square Bang Tourbillon 4-Day Power Reserve.
The case of the Square Bang Tourbillon 4-Day Power Reserve stands out through several key features that set it apart from previous models in the line. While its 42 mm diameter remains consistent with earlier editions, Hublot has opted for a slightly slimmer height of 13.2 mm. Notably, this model is the first in the collection to feature a case made entirely from 3D carbon. The name derives from its woven carbon fibre structure, whose vertical and horizontal stripes create a distinctive surface pattern. This is intended not only to produce a visual sense of depth—hence the “3D” in its name—but also to ensure high structural integrity. Another point of distinction is the reduced water resistance, which has dropped to 30 metres, compared with 100 metres for previous models in precious metals and ceramic, or 50 metres for sapphire crystal versions.
The matching square bezel is secured to the central case with six H-shaped titanium screws – a recurring design signature of Hublot. The caseback, too, is made from carbon fibre and features anti-reflective sapphire crystal, offering an unobstructed view of the openworked movement and its distinctive square bridges.
The particular appeal of a skeletonised watch lies in the fact that the wearer can observe the transmission of power within the movement directly through the dial: the energy stored in the mainspring barrel is gradually released, driving the gear train and ultimately reaching the escapement and balance wheel, which regulate the steady rhythm of the watch. In the case of the fully openworked dial on the Square Bang Tourbillon 4-Day Power Reserve, this process becomes a tangible experience. What stands out most is the continuation of the case’s design language within the movement itself: all bridges are either square or rectangular in shape, reflecting the same angular lines that define the outer case. The aesthetic is further enhanced by alternating satin-brushed and matte surfaces that create a distinct sense of depth.
To ensure visual clarity, the movement’s key components are arranged along the four sides of the dial: on the right at 3 o’clock, the winding mechanism transfers the rotational movement of the crown to the oversized mainspring; opposite, at 9 o’clock, sits the power reserve indicator, offering a reading of the watch’s four-day autonomy. At the top, positioned at 12 o’clock, the large mainspring barrel is clearly visible, while the tourbillon mechanism is prominently displayed at the bottom, at 6 o’clock.
At the heart of the Square Bang Tourbillon 4-Day Power Reserve lies the MHUB6023 manufacture calibre – the first movement within the Square Bang line to have been conceived from the ground up with a strictly square architecture in mind. Whereas previous Square Bang models housed the brand’s round UNICO chronograph calibre, a glance through the caseback of this latest edition reveals that the new calibre is anything but circular. It is built upon a square foundation, with intersecting right-angled bridges that lend the entire watch a coherent, geometrically unified appearance.
The movement is manually wound and offers an extended power reserve of 96 hours – or four days – made possible by the oversized mainspring barrel. The remaining reserve can be read via the indicator on the dial. The tourbillon features a silicon escapement, designed not only to enhance precision, but also to increase resistance to magnetic fields and temperature variations. Beating at a frequency of 21,600 vibrations per hour (3 Hz), the movement operates within the typical range for a tourbillon.
The strap of the Square Bang Tourbillon 4-Day Power Reserve is crafted from black rubber and features an embossed pattern that continues the square design language of the watch. A folding clasp made of black ceramic and black-coated titanium ensures a secure and comfortable fit.
With its consistent square design – extending from the case and dial to the movement and even reflected in the strap – the new Square Bang Tourbillon is arguably the most visually coherent model in the collection to date. At the same time, with a retail price of €109,000, it is also the most expensive piece within the Square Bang range. Unlike many other Hublot models, however, this watch is not subject to a strict limitation; instead, it joins the brand’s permanent collection as a regular production model.
