connected with each other and are located on a corresponding circular path so that an all around tilt preventing support ofthe inner profiled section 4 inside the outer profiled section 3 results for example four larger and four smaller inner contour sections 3 1 exist which are distributed around the inner profiled section 4 over more than 180 u00b0 for assuring the tilt preventing support the inner profiled section 4 is flattened only on two oppositely located long sides and has in its interior longitudinally extending screw channels 4 3 for mounting a mounting element of the head element 7 on the front face in this embodiment the inner profiled section 4 can be rotated around the vertical or linearly extending axis in the outer profiled section 3 if rotation around the vertical axis is to be avoided it is possible such as shown in fig4 for a transverse pin 4 4 to be conducted through the inner profiled section 4 which protrudes on both sides past the outside of the inner profiled section 4 and projects into holding grooves 3 4 on both sides which are formed in the inner contour of the outer profiled section 3 as fig2 b shows it is also possible to use a simple profiled tube with circular cross section as the inner profiled section 4 whose outer contour sections 4 1 are supported safe against tilting and slidingly in a corresponding manner by the rounded inner contour sections 3 1 the same as the inner profiled section 4 in accordance with fig2 a here too as in connection with fig4 a rotation prevention can be provided by a.