High Quality.
Color : Black
Polyurethane Tubing 6x4mm， Co2 Proof
Prevent Co2 leakage from the tubing
Save Co2 and long lasting
Standard air pipe size: 4mm internal diameter， 6mm outside diameter

Instruction:

Use hot water to soften the end of tubing before put that on your device (such as diffuser， bubble counter， check valve or regulator).
Connect the tubing to your device

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