A fastener assembly includes a bushing having a flange configured to be urged toward a work-piece, and an isolation spring configured to be positioned between the flange and the work-piece. The detonation wave produces a pressure in a coupling chamber that is substantially sealed when the detonation wave is generated. In order to adapt the width of the blow zone to the width of the corresponding strip material, said movable shutter member has an edge adjacent to the inside surface of the wall fitted with the blow orifices, and an edge adjacent to a side wall of the hollow box.