Active Air-Timer Options:Hydrofarm CO2 (1-20 cu ft per hour) with Timer is the 34 oz size

is the 34 oz size (pack of 6)

• Comfort Grip™ improves control and reduces hand fatigue

Take the "Natural Path" in encouraging the production of blooms

• Vegetative spectrum for beginning stages of plant growth

Active Air-Timer Options:Hydrofarm CO2 (1-20 cu ft per hour) with Timer is the 34 oz sizeDeliver growth boosting CO2 with our user friendly, easy to operate system. With its programmable timer, it will automatically maintain ideal CO2 levels for optimum growth. For small to medium size areas, select the COSYS; for larger than 10' x 10' areas, select the COSYS20. To use Hydrofarm's CO2 Flow Rate Calculator, click HERE NOTE: Current COSYS & COSYS20 now come equipped with a black rubber O ring that has replaced the white plastic washer.