Check the listing for details. TNB Naturals TNBCO2REF Refill Enhancer CO2 Canister Pack, 1 Pack. Color: REFILL, Condition: New. Listed at 19.99 USD. TNB Naturals TNBCO2REF Refill Enhancer CO2 Canister Pack, 1 Pack Features REFILL: The TNB Enhancer CO2 Refill Pack gives growers the ability to reuse the existing Enhancer bottle while saving money and reducing environmental footprint.NATURAL: The Enhancer is made from all natural, 100 percent organic ingredients which when activated create a blast of CO2 that can reach 1200 ppm in a 12x12x12 area.LONG LASTING: Reach 1200 ppm in a 12x12x12 area. Disperses high level of CO2 for 2 weeks!SAVES MONEY AND ECO FRIENDLY: Reuse the existing Enhancer bottle while saving money and reducing their environmental footprint.MAXIMIZE YOUR CROPS YIELD: The same great recipe in a convenient refill pack. WATCH YOUR YIELD INCREASE DRAMATICALLY! 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!