Device for fixing a roof box

The device has housings (1,2) with a pressure plate (2a) and a clamping lever (3), where the clamping lever is arranged in the housing from an open position to a closed position in a pivoted manner. A U-shaped bent clamp (8) is provided with a closed head (8e) and two arms, which are opposite to the head, where the free ends ends of the arms are mutually angled to each other. A wedge (7) is arranged between the arms for expanding the two ends of the arms.