One of the most complicated parts of setting up a network system is the selection of the serial cables to connect the network system to the serial devices in your network. CISCO cables are high performance and high quality. The cables have been tested by Cisco technical experts to ensure they meet the Cisco rigid quality standards.??The 75-120-ohm adapter cable connects Cisco 120-ohm E1 port adapters to 75-ohm unbalanced G.703 E1 lines. The adapter has an eight-pin RJ-48C connector on the 120-ohm side and dual BNC coaxial connectors (transmit and receive) on the 75-ohm side. Two switches on the 120-ohm side allow the outer conductor of the cable (the input port of the E1 port adapter) to be either isolated from or connected to a protected earth ground. The 120-ohm E1 ports of your port adapter connect to the 75-120-ohm adapter cable using RJ-48C connectors and Category 3 or Category 5 shielded foil twisted-pair (FTP) cable with 120-ohm impedance.