Abstract: A shelf, shelf system or partition is to be configured so that a rigid connection of the individual module units is guaranteed when they are stacked atop one another and when assembled next to one another. This is achieved in that U-shaped module units (1) have blind holes (7) that are placed at least approximately centrally to narrow sides (6) of carrying uprights (5). Module units (1) placed atop one another can be connected to one another by connecting elements (12) that can be inserted in blind holes (7) (FIG. 1 ).