for the transport of blank stacks to a packaging machine , there are re - usable cassettes which have chambers for receiving a multiplicity of blank stacks . the cassettes are filled with the blank stacks in a paper factory and are emptied in the region of the packaging machine . the cassettes are designed so that several emptied cassettes can be nested in one another and returned as a space - saving unit to the paper factory . furthermore , the cassettes are designed so that they can be transported by overhead conveyors and supported on downwardly directed carrier arms which include horizontally directed carrier spars having a step - shaped configuration which also accommodates different sizes of material reels associated with the packaging machine .