The bubble counter with check valve can prevent backflow when the pressure changes, which can damage the water pressure gauge and the CO2 cylinder. Is to install and use, a good choice to make your fish tank different. It can count the volume of carbon dioxide and provide factories with enough carbon dioxide. Features: VISIBLE CO2 OUTPUT: Carbon dioxide output is clearly visible, which can better supply enough CO2 to aquatic plants. SUITABLE FOR: G1/8 interface trim valve is suitable for single head solenoid valve. If not G1/8 interface, suitable for 4*6mm air hose (inner diameter 4mm and outer diameter 6mm). DURABLE AND EASY TO INSTALL: be made of alloy of aluminum, strong and sturdy. Besides, easy to install and disassemble. INSTRUCTION: CO2 source - compensation valve - solenoid valve - air tube bubbler - bubble diffuser - fish tank, pay attention to the CO2 flow direction during installation. WITH CHECK VALVE: With check function to prevent backflow when pressure changes, which can protect water pressure gauge and CO2 cylinder. Specification: Name: Bubble counter with check valve Color: silver + transparent Main material: aluminum alloy + acrylic Optional type: Single head/double head Single head: can connect with trim valve, G1/8 interface only Double head: connect with 6*4mm air hose (inner diameter 4mm, outer diameter 6mm) Size: Single head: 20*80mm Double head: 20*89mm Note: In the lush water tank, it is recommended to play 2-3 CO2 bubbles in 1 second.< /p> Package Information: Package Size: 10*2.5*2.5cm Package weight: 30g Plastic packaging