Joint Unit (Unidad Yunta), belonging to the series of the same name, integrates two separate white marble volumes arranged facing one another. The front faces of these volumes create profiles which complement each other when they come together, both bodies joining together and uniting to form a rectangle. This represents communication with the other. Serrano applies a different finish to the two pieces which must be interpreted within the meaning of the series. It is the faces, which confront each other and where communication arises, where the artist reserves the most delicate treatment of the piece with polished marble. This leaves the exterior part with a rugged finish created by bush hammering stone. As stated by the artist: "People who communicate, live together, shapes which adapt to one another, nuclei which together form a bright polished contact unit, nuclei with shapes united through these interior spaces which adjust, squeeze into one another, which can integrate into communities or which can be individuals."