In 2026, Patek Philippe introduced the Cubitus 5840P-001 as the inaugural Grand Complication of its Cubitus series. This timepiece features a skeletonized movement in a distinctive square shape combined with a perpetual calendar mechanism, encased in a platinum shell that measures 45 mm diagonally and 10 mm in thickness. Its unique design showcases a square silhouette with softened corners and a blend of polished and satin finishes across both the case and the bezel, accentuated by a baguette-cut diamond positioned at the 6 o'clock mark.

The timepiece includes a screw-down crown and a sapphire crystal case back, ensuring water resistance up to 30 meters. The dial, presented in a captivating sunburst blue, has been meticulously openworked with a horizontal strip pattern to reveal the intricacies of the movement's square-shaped mainplate and bridges. Hour markers in white gold, alongside rounded baton hands coated in luminescent material, enhance legibility. The perpetual calendar functions are arranged manually and include subsidiary dials for day, date, month, leap year, and a 24-hour indicator, complemented by an aperture for moon phases featuring a high-definition, metallized, and laser-engraved moon.

At its core, this watch is driven by the Patek Philippe calibre 28-28 Q SQU—a square-shaped skeletonized perpetual calendar movement measuring 28.5 x 28.5 mm and 5.04 mm thick, comprising 313 parts and utilizing 27 jewels. The movement is wound via a rhodium-plated off-centre 22K gold mini-rotor and operates at a frequency of 21,600 semi-oscillations per hour, with a power reserve of 38 to 48 hours. Observing through the case back, one can see the intricately openworked movement bridges, a rhodium-plated balance, the beautifully engraved mini-rotor adorned with the Calatrava cross and blue varnish, along with transparent jewels and blued screws. The watch is finished with a navy blue composite strap, textured with a fabric pattern, and detailed with contrasting cream stitching, fastened by a fold-over clasp in platinum.