in the bellows ridges 2 are all pressed out the lower walls 22 contact the corresponding upper walls 21 the bellows ridges 2 are warped toward the lower walls 22 as shown in fig1 c and layered neatly it is advantageous that the length of the upper walls 21 and that of the lower walls 22 having the indentations 3 when stretched are substantially the same to avoid generation of strain in the walls 21 and 22 such is attainable by appropriately designing the bellows ridges 2 this would advantageously apply to all the other embodiments of the present invention fig2 shows a bellows ridge 2 according to another embodiment of the present invention generally a plurality of such bellows ridges 2 are to be incorporated in a bellows container this applies to the other embodiments showing only a single bellows ridge this bellows ridge 2 has an indentation 3 in the lower wall 22 adjacent its inner hinge 24 when a pressure is applied on the container not shown vertically the inner hinges 24 of the bellows ridge 2 receive the pressure the upper wall 21 receiving a downward pressure and the lower wall 22 receiving an upward pressure the downward pressure on the upper inner hinge 24 is converted into a rotary moment working on the upper wall 21 and the upward pressure on the lower inner hinge 24 is.