this invention relates to a subrack with side walls connected by means of cross - pieces , in which electronic modules , particularly printed circuit boards , can be placed . the modules have terminal strips on their rear edges which can be inserted into electrical connectors facing towards them mounted in the rear area of the subrack at a predetermined depth from the plane of the front panel . through the design and arrangement of two mounting bars in the rear area of the subrack , using the same components of the subrack , different electrical connectors may be selectively mounted to receive terminal strips of electronic modules of different sizes .