Abstract: An apparatus for the bilateral blowing of a treatment gas onto a web-shaped material comprises a treatment space for the approximately rectilinearly moved web-like or sheet-like material, nozzle ribs arranged on both sides of the web-like or sheet-like material for introducing the treatment gas stream into the treatment space and radial fans for generating the treatment gas stream on the one hand and symmetrical extraction of the treatment gas from the treatment space on the other hand; each radial fan is installed into a 360.degree. spiral housing; the two radial fans are arranged point symmetrical at 180.degree. and each blow into a blow-out duct disposed on the longitudinal side of the apparatus; and each blow-out duct comprises a first region of constant or approximately constant cross-setion and a distributor piece with cross-section diminishing in the flow direction.