Web or sheet material is carried on air to advance the material in a fixed stable floating position through one or more decks of a treating plant, preferably a drier. Fixing chambers providing an air flow substantially parallel to the plane of the material and blow boxes with an air flow substantial perpendicular to said plane of the material are located adjacent each other on both sides of the material and are arranged to face each other mutually on the opposite sides of the plane of the material.
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