in the longitudinal direction of the opening edges p can be arranged closer to the side wall w than the locking projections l provided on the lower sides of the opening edges p thereby the clamp 1 which is shown in fig1 3 has in its use position an upper gripping jaw 4 which has a length greater than the lower gripping jaw 5 the locking projections u l can be slightly undercut as it is shown in fig3 as also shown in fig3 the hook shaped connection parts 8 9 have an outer contour which is preferably similar to the contour of the locking projections u l therefore the hook shaped connection parts 8 9 are also slightly undercut to be mounted on a cable duct the clamp 1 according to the present invention is placed at a small angle on the opening edges p of the cable duct upon the clamp 1 which is located transverse to the longitudinal extent of the cable duct c being pivoted back the hook shaped connection portions 8 9 slide over the locking projections u l and the clamp 1 becomes fixed on the cable duct c the elasticity of the gripping jaws 4 5 is so selected that they in their mounted and anchored condition are.