Cable separators work by coupling together two complete brake or shifter cables. The first cable, from your brake or shifter, terminates in the male end of the coupler, and is held fast with two, 2mm setscrews.
Then a second cable is sent out the female end of the coupler and on to the brake or derailleur. The head of the second cable is captured by the female end of the coupler.
We position the cable separators a few inches ahead of the frame couplers on a single bike and, on a tandem the same distance from the second set of frame couplers.
Each set of 3 separators consists of 2 shifter cable separators and 1 brake cable separator. Each separator requires 2 complete inner cables (wires). You will need 4 shifter inner cables, and 3 brake inner cables for one bike.