These kits aren't needed, but make life much easier. Individual colors of all signals are wired together in parallel, while the common to each signal head is wired individually. Further, resistors have to be wired in series with either the common or colors. These boards provide all that wiring, with resistors (included), and a set of 8-wire phone jacks to run wires out to individual signal heads using standard 8-wire flat cable with RJ45 jacks.