DFE-520TX 10/100Mbps Dual-Speed PCI Network Card supporting 32-bit Bus Master operation, the card provides a guaranteed performance for your networked PC. Bus Master transfers data directly between the card and the PC host, bypassing your computer host CPU to alleviate its workload. This allows your computer to concentrate on the application at hand, instead of the network operation task. The card's single RJ-45 connector connects to either 10BASE-T Ethernet or 100BASE-TX Fast Ethernet. 10/100Mbps speeds are auto-negotiated, completely without your need to intervene. In the fast 200Mbps full-duplex mode, the card's embedded flow control provides a means to protect your data against possible loss during transmission on the network. When connected to a LAN switch that supports flow control, the card receives signals from the switch regarding buffer overrun during peak usage periods. The card then delays transmission until the switch is ready again to accept new data.