Support suitable for supporting a plate in relation to a surface, comprising a base, suitable for resting against said surface, and two wings, which extend from said base, identifying a cavity suitable for containing the lower edge area of said plate and said cavity containing at least one regulation and/or locking device suitable for cooperating with a side (101, 102) of said plate, said side being one of the two main surfaces of the plate, so as to adjust and/or lock the plate in a predefined position with respect to said surface characterized in that said regulation and/or locking device comprises: - two gibs facing each other, wherein each gib comprises: i) a support surface, positioned outwards with respect to the gib, wherein one gib has a support surface resting on one side wings and wherein the other gib has a support surface suitable for resting on a respective side (101, 102) of the plate; ii) two positioning surfaces, inclined with respect to the support surface and positioned outwards with respect to the gib, in an opposite direction to each other, in such a way that between the two opposite gibs two compartments are created, opposite each other; - two positioning means, housed in said compartments, interacting with the positioning surfaces of the two gibs, in such a way as to move their position locking the plate interact at the same time on each positioning surface of both gibs; - control means manoeuvrable so as to activate the positioning means, wherein the control means are suitable for moving, at the same time, the positioning means in the respective compartments, moving them closer to or further away from each other respectively. - two gibs facing each other, wherein each gib comprises: i) a support surface, positioned outwards with respect to the gib, wherein one gib has a support surface resting on one side wings and wherein the other gib has a support surface suitable for resting on a respective side (101, 102) of the plate; ii) two positioning surfaces, inclined with respect to the support surface and positioned outwards with respect to the gib, in an opposite direction to each other, in such a way that between the two opposite gibs two compartments are created, opposite each other; i) a support surface, positioned outwards with respect to the gib, wherein one gib has a support surface resting on one side wings and wherein the other gib has a support surface suitable for resting on a respective side (101, 102) of the plate; ii) two positioning surfaces, inclined with respect to the support surface and positioned outwards with respect to the gib, in an opposite direction to each other, in such a way that between the two opposite gibs two compartments are created, opposite each other; - two positioning means, housed in said compartments, interacting with the positioning surfaces of the two gibs, in such a way as to move their position locking the plate interact at the same time on each positioning surface of both gibs; - control means manoeuvrable so as to activate the positioning means, wherein the control means are suitable for moving, at the same time, the positioning means in the respective compartments, moving them closer to or further away from each other respectively.