Features:

• This CO2 bottle cap is suitable for most kinds of DIY reactor
• Easy to use. Just screw the bottle cap on the drink bottle. Easy and sealed without letting the air out easily
• Plastic material makes this bottle cap uneasy to rust and safe for your fish and water plant
• For people who love DIY CO2 setup, this bottle cap is a helper when they are doing the process of generating CO2
• If the water plant in your fish tank / aquarium is growing slowly and needs more CO2, this bottle cap may help you
• With the 2 holes, you can add both tube and other tool like bubble counter or other things to help you know and control the process