As previously mentioned, the primary purpose of the retainer is to hold a PCB in place and the secondary purpose is to transfer heat from the PCB to a cold wall. For applications requiring shock and vibration or thermal requirements beyond what a Wedge Lok alone can provide, Schroff also offers heat frames and clamshell CCAs. In fact, approximately 30% of all Wedge Loks and Card Loks are attached to frame or clamshell CCAs.