THESE BAGS ARE GREAT THE SIMPLEST AND EASIEST WAY TO BOOST CO2 LEVEL IN YOUR GROW ENVIRONMENT. ALL YOU HAVE TO DO IS SIMPLY PLACE ONE BAG NEXT TO EACH LIGHT FOR ENOUGH CO2 TO BE CREATED TO LAST ON FULL GROW CYCLE. THE BAGS RELEASE CO2 WHEN THEY ARE INTRODUCED TO HEAT SO YOU HAVE GREAT CO2 LEVELS WHEN YOUR LIGHTS ARE ON WITH OUT THE NEED TO REMOVE THE BAG OR SET TIMERS FOR WHEN THE LIGHTS GO OFF ON SOME CO2 SYSTEMS.