The design, assembly, and selected materials for Calmark Card Guides are an economical solution for PCB retention in sheet metal applications. They feature zero entry force, a wide lead-in for easy card entry, and a simple snap in design. Since the card guides do not provide much protection for shock or vibration, they are best suited for static applications such as general computing in laboratories that have static equipment, data collection or communication centers, equipment in racks, or ground support equipment.