A reliable swiveling fastening mechanism that allows a plate to be horizontally, obliquely and vertically fastened comprises, in the position of use: a vertical supporting profile to be arranged at the top of the mast, coaxially to the mast; two parallel backing plates mounted so as to swivel on the supporting profile and interconnected on one side by a plate carrier fastening component and on the other side by a U-shaped vertical position stop attached to the backing plates and arranged in such a way that the plate carrier fastening component is parallel to the supporting profile when the supporting profile is in contact with the vertical position stop; and a retractable stop supported by at least one backing plate so that the plate carrier fastening component forms an angle between 10° and 80° with the supporting profile when the supporting profile is in contact with the retractable stop.