Abstract: A process and a device for substantially eliminating tolerance-dependent variations of a preselectable space between the components of an optical communication apparatus is described. U-shaped recesses are provided in a metal casing for pressing in flange-type necks of, for example, optical transmitting and receiving devices. The parallel arranged devices are so spaced from each other that they are not subject to tolerance-dependent variations. For this purpose the metallic necks are coated with a plastic layer, and ribs provided at the lateral walls of the U-shaped recesses dig into the plastic layer. The necks are pressed in precisely at a predetermined spacing by means of a gauge. By the application of varying degrees of pressure when the ribs are pressed in on one side and the other side of the neck, one of the U-shaped recesses can be off-center.