flexibility of the spring clip 22 in the axial direction it should be noted that these zones or regions 57 enable the spring force of the spring clip 22 to be given different magnitudes or values in the axial direction and in the radial direction so that it is possible to achieve optimum adaptation or accommodation to existing flat mounting conditions in other words appropriate selection of the cross section of the narrow regions or zones 57 enables the axial resistance of the spring clip 22 to be so selected as to be much less than the radial resistance the axial transmission of the force from the stationary flat 14 to the spring clip 22 is accomplished by means of the actuation head 24a of the adjusting or setting screw 24 the actuation head 24a of the adjusting or setting screw 24 likewise extends through an opening or aperture 56 in the second limb or leg 41 of the spring clip 22 so that this adjusting or setting screw 24 is also accessible and adjustable when the spring clip 22 is already mounted or fitted it should be noted that the adjustment or setting block or block member 23 located at each end or end portion of the stationary flat 14 comprises two.