The ExHale Homegrown CO2 cultivator works 24 hours a day with no need to refill bottles or invest in a complex CO2 system. The vented cultivator unit contains a non fruiting mycelial mass that produces CO2 continually for up to six months. Because it uses no electricity and generates no heat, it doesn't need to be turned on or off it simply sits and does its job. The ExHale cultivator is designed for small to medium grow spaces, providing enough CO2 for four to six plants. Please note: Homegrown CO2 is a ready to use product. They come already activated and are ready to go.