Abstract: A universal beam for supporting a movable load is capable of handling heavier loads than prior systems and can be constructed of aluminum extrusions or other materials allowing high accuracy, and has good torsional stiffness and other desired properties. A symmetrical U-shaped profile extrusion has parallel shanks extending downwardly from a top and a connecting member between the shanks. Between the connecting member and the bottom of the extrusion a load supporting, guiding and driving volume is provided. The shanks between the connecting member and the top, except at the corners, have a thickness that is at most 4% of the extrusion width. The connecting member includes a central wall, first and second drums adjacent locally reinforced portions of the shanks, a generally flat bottom portion, and inner walls substantially parallel to the shanks and having a substantially flat inner surface.