4 Pcs Air Diffuser Cap Aquarium Pump Fish Accessories Bottle Caps Live Plants Description _x000D_ _x000D_ Searching of a CO2 bottle cap? Our CO2 bottle will be the best choice for you. Made of plastic material, durable enough for your long-term use. Practical and portable design, ensures its popularity. _x000D_ _x000D_ Features _x000D_ _x000D_ - Color: As Shown. _x000D_ - Material: ABS. _x000D_ - Size: 3.30X3.30X3.00cm/1.30X1.30X1.18in _x000D_ - Add and control the amount of CO2 available to your fish and plants, add essential CO2 into your aquarium water . _x000D_ - Easy to set up, and excellent quality, can be used for a long time . _x000D_ - Can be directly screwed onto carbonated beverage bottles, safe, durable and airtight . _x000D_ - Suitable for all kinds of DIY reactors to meet your needs. _x000D_ - It's practical and convenient, and strong in functionality. 4 x bottle caps _x000D_