This article describes mechanical differences in behaviour of groove squared profiles, which are made of carbon composite material. Specimens were made by winding of prepreg carbon fibre filament around Rexroth profile. Afterward was epoxy of first specimen cured in shape form and the epoxy of second specimen was cured in vacuum chamber. This way was made two difference internal structures with different mechanical properties. Their properties were tested by bend test. Bend test lasted till first hearable cracking and not until complete breakage of material. By this way, we describe carbon composite material by properties before even small breakages in internal structure. Measurement data can be used for comparisons with simulation FEM analysis. This is especially important in developing new products. This work was done at University of Žilina Faculty of Mechanical engineering, Department of Design and Mechanical Elements. The tests were performed on tensile test machine LabTest 5.20ST type: KAP-S.