Longitudinal locking mechanism for insert member on the body sheet metal of a road vehicle

The device (10) has a longitudinal locking plate (13) linked at an interior face of an insert by pair of elastic link. The locking plate is maintained at a predetermined distance from the interior face of the insert by having two side boards (14,15). The plate comprises a locking structure (20,21) on its upper face, where the structure locks the plate against downstream transversal end of an opening provided at the structure.