Spacer suitable for being fixed to a first C-shaped profile P1 and to a second C-shaped profile P2, the first profile P1 being adapted to be bound to a first surface and the second profile P2 being adapted to be bound to a second surface, an insulating material being arranged between the first surface and the second surface, said spacer comprising: - a support adapted to be bound to the first profile P1; - a stem adapted to be coupled to the support; - a clamping flange which comprises a base portion and is adapted to be bound below the stem and above the second profile P2; wherein the support comprises first fixing means (20, 34, 35) and the stem comprises second fixing means (36, 40, 41) so that the first fixing means (20, 34, 35) can be coupled to the second fixing means (36, 40, 41) in variable positions so as to vary the overall height of the spacer as well as to choose and set the height according to the thickness of the insulating material; wherein the support comprises a cylindrical body in which a hole is formed at the top, characterized by the fact that at least two side seats (34, 35) are formed laterally and are arranged at different heights of the cylindrical body, and wherein the stem comprises an elongated portion from which at least one tooth (40, 41) protrudes laterally and has a homologous shape to the at least two side seats (34, 35), so that the elongated portion can be inserted into the hole and the at least one tooth (40, 41) can be inserted into one of the at least two side seats (34, 35); and that the stem comprises a tip with at least one arched face on which first knurls are formed and wherein a central hole is formed in the clamping flange, second knurls being formed in the inner surface of said central hole, in correspondence of an angular portion, so that when the tip is inserted in the central hole, the first knurls and the second knurls interfere with each other so as to clamp the clamping flange to the stem. - a support adapted to be bound to the first profile P1; - a stem adapted to be coupled to the support; - a clamping flange which comprises a base portion and is adapted to be bound below the stem and above the second profile P2; wherein the support comprises first fixing means (20, 34, 35) and the stem comprises second fixing means (36, 40, 41) so that the first fixing means (20, 34, 35) can be coupled to the second fixing means (36, 40, 41) in variable positions so as to vary the overall height of the spacer as well as to choose and set the height according to the thickness of the insulating material; wherein the support comprises a cylindrical body in which a hole is formed at the top, characterized by the fact that at least two side seats (34, 35) are formed laterally and are arranged at different heights of the cylindrical body, and wherein the stem comprises an elongated portion from which at least one tooth (40, 41) protrudes laterally and has a homologous shape to the at least two side seats (34, 35), so that the elongated portion can be inserted into the hole and the at least one tooth (40, 41) can be inserted into one of the at least two side seats (34, 35); and that the stem comprises a tip with at least one arched face on which first knurls are formed and wherein a central hole is formed in the clamping flange, second knurls being formed in the inner surface of said central hole, in correspondence of an angular portion, so that when the tip is inserted in the central hole, the first knurls and the second knurls interfere with each other so as to clamp the clamping flange to the stem.