Abstract: A top or bottom part made of sheet metal for a module chassis has a surrounding frame and guide rails that are positioned between the front and rear frame strip and aligned in the direction of insertion for the mounting of the circuit board of a plug-in module. The guide rails are U-shaped in cross section and include a bottom and two sidewalls. The sidewalls of the guide rails have at least one lateral void. The voids can be located on both sidewalls of the guide rail and can be opposite each other in pairs. The voids of the sidewalls correspond with at least one contact area at the lower edge of the circuit board.