The Titan Controls Atlas 3 Day/Night CO2 Monitor / Controller is a sophisticated device designed for monitoring and controlling CO2 levels in indoor environments, particularly useful for hydroponics setups. With a built-in ppm photocell, this controller allows for precise adjustments to keep CO2 levels optimal during day and night cycles. The Titan Controls brand is known for producing reliable and high-quality environmental control products, making this CO2 monitor a valuable addition to any home or garden climate control system.