Keysight N2818 User Manual page 15

Using the Probe
Or,
Connect the red and black extreme temperature banana-to-socketed tip
adapters to the extreme temperature differential extension cables which
are already connected to the existing probe cables.
Figure 8 Connecting the Extreme Temperature Banana-to-Socketed Tip Adapters
Keysight N2818/9A Differential Probes User Guide 15