This object has a metal frame with open sides and a door on the back. The front two thirds of the frame contain a roll-out unit with two hinged card cages. The cages are filled with IBM modules. At the top there is an add on bracket with one screw protruding from the middle. The back third of the frame is for cabling.
International Business Machines (IBM)
Found on the label on the right front door of the unit.