Abstract: The winding cores are flangeless and adapted to receive magnetic tapes. For reasons of compact packaging, it is desired to be able to stack several reels of tape securely for transport. For this reason, the winding core is designed so that the height of the winding surface is equal to or slightly greater than the width of the tapes to be wound on it. In addition, the surfaces between the internal and external circumference or on the internal circumference of the winding core have projections which project upwards or downwards from the medial plane of the core by half the total height of the core. When several cores are stacked above one another, these projections interlock so that the winding surfaces are stacked as closely together as possible.