each of one or more devices to be detachably attached to a mechanical substructure includes rails on opposed sides with insertion / extraction mechanisms . each of a plurality of pairs of guides mounted on the substructure slidably receives and retains a respective set of rails upon attachment of the devices . the insertion / extraction mechanism includes one or more pivotable handles associated with each device for retaining the device with the substructure . a spring extending from a rail makes electrical contact with electrostatic discharge ground pads on the substructure to discharge existing static charge from the device prior to electrical engagement between an electrical connector on the device and an electrical connector on the substructure . an apertured plate of the substructure includes a plurality of apertures through which the devices are inserted / extracted . a face plate may be hingedly attached to and removable from the apertured plate to cover all of the apertures therein that accommodate insertion / extraction of the devices .