TNB Co2 Enhancer is made from 100% organic material and are refillable. TNB Co2 Enhancer Canisters are self activated, meaning there is no CO2 wastage. Up to 1200 ppm over 2 weeks in area of 3.65 x 3.65m. No heat produced and lower levels on CO2 emitted during lights of period. Shake once a day or every 2 days, depending on area size.