The 263A with the 94 (2 Amp) option installed is equipped with two cell cables: a three terminal (part # C0345) cable, and a four terminal (part # C0366) cable with an additional gray-colored Sense lead. For working with currents above 200mA, one should use the four terminal cable (if only using three electrodes, the Sense lead is connected directly to the working electrode, with the working lead connected above it), and you must operate the system in High Speed mode. The purpose of bringing the sense lead out to the cell is that when working at higher currents, it may be important to eliminate the IR drop error resulting from the working electrode lead an alligator clip. In bringing the Sense lead out to the cell, you are then required to run in High Speed mode for the electrometer to operate correctly at the higher currents.