A clamp unit, for use in conjunction with three similar clamp units to secure together two substantially orthogonal universal beams, said clamp unit comprising a first retention section with a first connection part and a second retention section with a second connection part, said first and second retention sections (101a, 101b) being inter-connected via the first and second connection parts (102a, 102b); wherein a first cut-out is provided in the first retention section and facing a second cut-out provided in the second retention section, said first cut-out formed for accommodating portions of a flange of a first of the orthogonal beams and said second cut-out formed for accommodating portions of a flange of a second of the orthogonal beams; wherein the first cut-out is partly defined by an inner wall part of the first retention section, an abutment face of the first connection part, and an inner wall part of the second connection part, and wherein the second cut-out is partly defined by an inner wall part of the second retention section, an abutment face of the second connection part and an inner wall part of the first connection part, said abutment faces (105a, 105b) being orthogonal to each other; and wherein the first retention section holds a first throughgoing bore being orthogonal to a second throughgoing bore provided in the second retention section, said first throughgoing bore being parallel to the abutment face of the first connection part, and said second throughgoing bore being parallel to the abutment face of the second connection part; characterised in that the first cut-out is further defined by a first flange insertion opening having first and second angled sidewalls (108a, 107b), said first angled sidewall formed in the first retention section at a first obtuse angle to the inner wall part of the first retention section, and said second angled sidewall formed in the second connection part at a second obtuse angle to the inner wall part of the second connection part; and in that the second cut-out is further defined by a second flange insertion opening having third and fourth angled sidewalls (108b, 107a), said third angled sidewall formed in the second retention section at a third obtuse angle to the inner wall part of the second retention section, and said fourth angled sidewall formed in the first connection part at a fourth obtuse angle to the inner wall part of the first connection part. wherein a first cut-out is provided in the first retention section and facing a second cut-out provided in the second retention section, said first cut-out formed for accommodating portions of a flange of a first of the orthogonal beams and said second cut-out formed for accommodating portions of a flange of a second of the orthogonal beams; wherein the first cut-out is partly defined by an inner wall part of the first retention section, an abutment face of the first connection part, and an inner wall part of the second connection part, and wherein the second cut-out is partly defined by an inner wall part of the second retention section, an abutment face of the second connection part and an inner wall part of the first connection part, said abutment faces (105a, 105b) being orthogonal to each other; and wherein the first retention section holds a first throughgoing bore being orthogonal to a second throughgoing bore provided in the second retention section, said first throughgoing bore being parallel to the abutment face of the first connection part, and said second throughgoing bore being parallel to the abutment face of the second connection part; characterised in that the first cut-out is further defined by a first flange insertion opening having first and second angled sidewalls (108a, 107b), said first angled sidewall formed in the first retention section at a first obtuse angle to the inner wall part of the first retention section, and said second angled sidewall formed in the second connection part at a second obtuse angle to the inner wall part of the second connection part; and in that the second cut-out is further defined by a second flange insertion opening having third and fourth angled sidewalls (108b, 107a), said third angled sidewall formed in the second retention section at a third obtuse angle to the inner wall part of the second retention section, and said fourth angled sidewall formed in the first connection part at a fourth obtuse angle to the inner wall part of the first connection part.