A horizontal roll stand includes upper and lower back-up rolls, removable work rolls, a balancing device for supporting the upper work roll, and a vertical adjustment device for the lower back-up roll. The work rolls are removed and a press device for straightening pressing of a flat metal product is inserted into the roll stand. The press device includes opposing upper and lower press frames that are displaceable relative to each other. The upper press frame and the lower press frame have one of a selectively moveable pressing die or opposing selectively moveable table with a trough for immersion of the pressing die to selectively press and flatten defects in the flat metal product. The upper press frame includes carrier elements which contact a balancing device of and for support within the roll stand. The lower press frame has support elements for being supported on stanchions of the roll stand.