TNB Naturals The Enhancer CO2 Generator 240g Refill PackIn Store Location: @H27 TNB Naturals The Enhancer CO2 Generator 240g Refill Pack The CO2 Refill Pack gives growers the ability to reuse their existing Enhancer bottle while saving money and reducing their environmental footprint at the same time. Simply empty the contents of the original bottle and give the bottle a quick rinse. The contents of the Refill Pack can be added and instantly CO2 is once again available for use.