I think you are talking about Helix Controls. The night time temp drop cord, plugs into the thermostat and into the timer you set it so when the timer cuts on the lights the temp goes up and when the timer cuts off the lights it drops the temp. I use it and it works wonderful. Different people say different things as far as where to put the temp probe. Say you have cages stacked 4 high if you put the probe in the bottom cage the top cages will be a little warmer. If you put the probe in the top cage the bottom cages will be cooler.I would take some 1 by 4 lumber and use them between each cage. That will allow air flow so the bottom cage does not heat the one on top of it.Then you could place the temp probe in the center cages.