A gas blower device for blowing gas onto a face of a traveling strip of material. The device has at least one hollow box fitted with a plurality of tubular nozzles pointing towards the face in question of the strip of material. On the side facing towards the face in question of the strip of material, the hollow box presents a surface of profile (P) that varies in at least one given direction (D) symmetrically about a midplane (Q) perpendicular to the plane of the strip. The tubular nozzles are fastened via their roots to the varying-profile surface in such a manner that their respective axes are essentially orthogonal to said varying profile at the point in question, said tubular nozzles having respective lengths that are selected so that the outlet orifices lie in a common plane substantially parallel to the plane of the strip.