Abstract: A carder for manufacturing non-woven materials from fibrous material which includes at least one draw-in roller, and a licker-in roller following the draw-in roller and rotating in the same direction. There are at least two worker rollers of the same diameter following the licker-in roller, the two worker rollers rotating in the same direction and at a greater speed than the licker-in roller. At least one doffing cylinder cooperates with the last of the worker rollers. Further worker rollers follow the two worker rollers, with the various worker rollers being separated by transfer regions between adjacent rollers. The relative speeds and the spacings between adjacent rollers are adjustable to control the proportion of fibrous material that can be returned to previous worker rollers or sent to succeeding worker rollers. An air-guiding box projects into at least one of the transfer regions, the box being adjustable in height and width.