Described is a new multilevel article comprising a multitude of ducts and, in each duct in the direction of flow, at least one area which generates turbulence, forms an open duct section, is connected to the duct wall, and forms a baffle for the incoming flow and a stall strip for the outgoing flow. The described article has a plurality of successive interconnected duct structures which form a step-like transition in relation to each other in the direct of flow.