Abstract: A retainer for retaining an electronic module, like a printed circuit card, in the slots of a cold plate or other holder, comprising a rail mounted to either the module or holder. An end wedge is fastened to one end of the rail so as to provide a stop for other, typically wedge-shaped bodies, slid onto the rail. Both the rail and wedge bodies are particularly configured so that the wedge bodies remain aligned, or are precluded from rotating about the rail or otherwise becoming misaligned. The present invention thus provides an easily assembled retainer, which avoids the use of specially manufactured free-floating screws.