What if you're installing central air conditioning for the first time, are installing a Honeywell Prestige thermostat and don't have enough thermostat conductor wires in the wall to do so? You'll want this module, then.

This wiring module connects to "K" terminal on Honeywell Prestige thermostats and separates into "Y" and "G" signals at furnace or air handler equipment. Intended to be used in conventional and heat pump systems requiring one wire more than is available.