The Exhale CO² bag cultivates carbon dioxide 24 hours a day with no need to refill bottles or use expensive production units. Maintenance Free: No heat, No electricity, Just CO² . A continuous shower of carbon dioxide directly onto your plants is the most efficient way to deliver CO² . Placing the bag slightly above the level of your plants will insure they receive the carbon dioxide they need. The regular sized Exhale CO² bag is designed for small to medium grow spaces, or more specifically 1 bag will provide 4-6 plants with the CO² they need. It can be used for both vegetative plant growth as well as for fruit and flower production. The ExHale bag also comes in XL size for larger growing areas.