One-piece rigid covers for disc-bound fold-over binding system and use of composite material for making the same

A cover (2) for disc-bound, fold-over binding systems, comprising a series of parallel T-shaped slits (7), wherein the long leg (10) of each T (7) is disposed at an angle of 90° with a straight edge (8) of the cover, and extends to this edge (8) of the cover, characterized by the fact that the cover consist of a one-piece sandwich panel containing two rigid outer layers (12A, 12B), which are permanently attached to a flexible core layer (13), wherein the sandwich panel is provided with an area which runs parallel to the edge (8) of the cover wherein between 0.1% and 100% of the outer layers (12A and 12B) of the sandwich panel is removed.