We have two in MINT condition. This is the CO2 measuring device that is used in conjunction and is controlled by the “C.A.P.” Brand “AIR4” Atmospheric controller. This is the piece that measures the CO2 Level in the grow room and it plugs directly into the “AIR4” Atmospheric controller unit. If you buy this unit you must buy the matching “AIR4” unit that accompanies it. We will not sell them separately. The other unit controls this unit.