Device for fastening a first component on a second component

Device for fastening a first component with a through opening on a second component with a trough opening being essentially rectangular in cross section, comprising a first fastening element which comprises a radial flange on one end and a shaft section with rectangular cross section, which is insertable into the through opening of the second component, wherein the flange abuts against a surface of the second component, and comprising a second fastening element which relative to the first fastening element is at least partly axially moveable, but borne torque proof, which second fastening element comprises an axial bore for receiving a fastening screw guided through the through opening of the first component being placed against the flange of the first fastening element and through the flange of the first fastening element, wherein the first fastening element comprises at least one first section of a first, harder material and at least one second section of a second, softer material, wherein the second fastening element upon screwing the fastening screw into its axial bore is pressed against the second section of the first fastening element and thereby deforms the same such that the second section abuts in a sealing manner on the surface delimiting the through opening of the second component.