A device used in the installation of a surface of ceramic parts that are levelled and aligned using a securing product. The device includes: a base, with an orthogonal cross-shaped structure formed of four arms, having an undulating surface; and at least two flexible planar attachments projecting up from the base and positioned symmetrically along the length of the base. The opposing planar surfaces of each of the flexible attachments including side ribs for slidably mounting and guiding upper bodies which, by applying pressure, contact with the upper surface of multiple covering parts (P), thereby being levelled.