The CAP  CO2 Regulator/Emitter will allow you to maintain ideal CO2 levels for optimum growth. It features an accurate, easy to adjust CO2 flow meter, a pre-set regulator that never needs adjusting, and solenoid valve. Each unit also comes with the tubing needed to disperse the CO2 evenly throughout your room by attaching the tubing to the back of an oscillating fan for even dispersion. If you are using this without a digital CO2 controller, you will need to use a timer (The Grasslin Grounded Timer is recommended). The flow rate is adjustable from .5 - 15 Cubic Feet Per Hour.