The WS-X4920-GB-RJ45 is a discontinued half-card Ethernet module by Cisco, featuring 20 ports with 10/100/1000BASE-T connectivity. It supports full or half-duplex operation at 10/100/1000 Mbps speeds, utilizes RJ-45 connectors, and has a maximum cabling distance of 328 ft. The module includes LED status indicators for monitoring.