Calculation of the optimum cross-section of slender struts strained for buckling and calculation of the appropriate strength check according to Johnson, Tetmajer, Euler and Secant method. Simple definition of the strut type - 40 types of predefined cross sections.Used standards: DIN 1025, 1026, 1028, 1029, 1024, AISC W, S, C, L, LU