A packaging unit formed from a sheet of material having an inner surface, an outer surface and one folding axis dividing the sheet into a first region and a second region. The inner surface includes an inner edge portion and an outer edge portion, wherein one of the inner edge portion and the outer edge portion of the edge zone of the first region is provided with adhesive, and the other of the inner edge portion and the outer edge portion of the edge zone of the first region is adhesive-free. One of the inner edge portion and the outer edge portion of the edge zone of the second region is provided with adhesive, and the other of the inner edge portion and the outer edge portion of the edge zone of the second region is adhesive-free in a complementary manner to the edge zone of the first region.
