BAZHOU Stainless Steel One Way Check Valve for Anti-Backflow Non-Return Tubing Regulator Diffuser in Aquarium System The Pneumatic Check Valve can prevent the aquarium from water flowing back, which is caused by the decrease, and keep the function and service life of Carbon dioxide bottle. When used in the Ozone generator, air check valve can prevent the Ozone from flowing back to the air pump and eroding the propeller. Aquarium non return check valve can protect the power head from the water flowing back which is caused by power cut. Single check valve is easy to install, requires no additional tools and can be attached to any place you like in seconds. These Stainless Steel One Way Check Valves are suitable for CO2 supply system in fish tank, aquarium and others. Color: silver Size: 398mm Quantity: 2pcs Kind tips: 1.As different measuring methods,it will occur 1-3 cm deviation about the items,please ensure that it is okay for you before ordering. 2. Because of different monitors and lamplight, the picture may not reflect the actual color of the item, really thank you for your kind understanding. 3. Only the above package contents, excluding other products.