Cisco 8 Port X21 Spare 4Mbit/s networking card

8 - Serial X21 Port Adapter for Cisco 7200 Family Routers Increasing demand for bandwidth-intensive services and wide-area network (WAN) connectivity requires that network administrators maximize the capacity and efficiency of network routers. Cisco Systems' serial port adapters provide network administrators with flexible options for a broad range of port density requirements. Cisco's eight-port serial port adapter enhances network performance at a low price per port---making them a cost-effective solution for maximizing router efficiency.