The Keysight E2621A ac-coupled, balanced adapter allows connection to differential communications signals by terminating the signal into 100, 110 or120 ohm. It also adapts various connector styles (i.e., bantam, RJ48C and Siemens) to the oscilloscope's 50 ohm; BNC input. You can select the termination impedance using the built-in, three-way switch. The AutoProbe interface allows the Keysight Infiniium oscilloscope to recognize the Keysight E2621A and read the termination switch setting. Furthermore, Keysight Infiniium will flag you when the switch setting differs from the standard's required termination impedance.