The pneumatic check valve can prevent the aquarium water from flowing back, which is caused by the decrease, and keep the function and life of the carbon dioxide bottle. When used in ozone generator, air check valve can prevent ozone from flowing back to the air pump and propeller erosion. Aquarium check valve Non-return valve can protect the power head from backflowing water which is caused by power outage. Simple check valve is easy to install, requires no additional tools and can be attached to a place where you want in seconds. These stainless steel One Way Check Valves are suitable for CO2 supply system in fish tank, aquarium and others.