This involves two different spiral cables, one inside the other, which spiral in opposite directions so that they do not get caught on each other when moved. The advantage of this is that different cable types can be used in an application to save a great deal of space.
The outer cable has a larger connection for the power supply and the inner spiral has a smaller cross section with pilot wires. These cables are extremely versatile. For example, they are needed in the medical field for raising and lowering tables and beds.