Check the listing for details. TNB Naturals TNBCO2REF Refill Enhancer CO2 Canister Pack, 2 Pack. Condition: New. Listed at 36.95 USD. TNB Naturals TNBCO2REF Refill Enhancer CO2 Canister Pack, 2 Pack The Enhancer now comes in a convenient refill pack! The TNB 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. Boosting plant production and improving overall health, CO2 is an essential element of photosynthesis and often one of the most overlooked components of plant growth. The TNB CO2 Refill Pack consists of the same great recipe while combining convenience and an amazing option for those looking for passive CO2. Research has shown that plants can use up to five times the CO2 that naturally occurs in the air. With The Enhancer known for delivering levels of CO2 only comparable to a propane or natural gas burner, there is no question many growers will be turning in their tanks and introducing CO2 with this safer and all natural method. Fast and Free Shipping You're already purchasing the item. Why pay additional for shipping, especially slow shipping? We get your order shipped out within 1-business day and delivered to your doorstep as quickly as possible. Competitive Pricing With our dynamic pricing model, our prices are always competitive. Our prices are some of the lowest that you will find on the internet. Rest assured that you're getting a good deal when purchasing with us. 30-day Money Back Guarantee We are committed to making sure that you leave this transaction satisfied. If you're unhappy with the product for any reason, you may return it back for your money-back or a replacement within 30 days. No questions asked!