head 31 the movement a between the fastener 6 and the tube shaped extension 5 is limited by the distance between the head 31 and the catch ring 36 as soon as the inner sleeve part 24 adjoins the catch collar 36 during mounting of the fastening element a subsequent attachment between the two sleeve parts 23 and 24 is achieved thus shortening the tube shaped extension 5 fig2 shows a further possibility of how the movement a can be limited in axial direction in this case latch like parts 37 are arranged in the walls of the tube shaped extension 5 within the inner space 11 of the tube shaped extension 5 which limit the movement direction of the locking element 13 that is attached to the fastener 6 towards the upper end during corresponding load application on the fastening element these latches 37 which are bent towards the inside achieve a subsequent movement of the locking element 13 in the axial direction of the fastener 6 fig2 and 28 show an example in which the locking element 13 is constructed as a tube shaped sleeve with two latches 38 that protrude in the axial direction and on whose free ends catch elements 39 are arranged which are directed toward the penetration.