The smartphone case is available in two versions: in calfskin and, the deluxe version, snakeskin, tanned in Italy. Both share a common characteristic: the colour of the material changes as the temperature or weather change or when the pressure rises. It is one of the pieces in the collection by The Unseen, a company formed in London in 2014 which produces leather accessories and products capable of changing appearance and transforming from red to black, or from green to blue, in a short time. This is not the first experiment of this type, but the founder of The Unseen, Lauren Bowker, who graduated from the Manchester School of Art and designed a chemical compound that enables the ink to change colour in response to carbon monoxide, after several experiments, managed to transform her project into a real company, thanks to its partnership with the British department store chain The Selfridges. The Unseen products, in limited edition, are hand-painted and vary in price from 35 to 1,750 pounds. The collection also includes wallets, bags and backpacks.