MyCO2 – Mycelium Derived Carbon Dioxide are CO2 bags perfected. Unlike all the other CO2 bags that "come cultivating CO2 even before you get out of the checkout line," MyCO2 has the patent pending customer activation technology, postponing the CO2 cultivation until you get it home and are ready to use it. One CO2 bag provides enough carbon dioxide for flowering or vegging plants in a 4 ft x 4 ft grow tent with cycled exhaust. Use during the Bloom during the flowering stage. Use during Grow during the veg stage. We recommend safely placing multiple MyCO2 bags above the highest level of your plants to insure they receive the CO2 as it is generated.