SincereetaliThe bubble counter with check valve can prevent backflow when the pressure changes, which may damage the water pressure gauge and CO2 bottle. Is to install and use, a good choice to make your aquarium different. It can count the volume of carbon dioxide and provide plants with enough carbon dioxide. Features: VISIBLE CO2 OUTLET: The carbon dioxide output is clearly visible, which can better provide enough CO2 to aquatic plants. SUITABLE FOR: The G1 / 8 interface trim valve is suitable for single head solenoid valve. If not G1 / 8 interface, suitable for 4 * 6mm air pipe (inner diameter 4mm and outer diameter 6mm). DURABLE AND EASY TO INSTALL: Be made of aluminum alloy, strong and sturdy. Also, easy to install and disassemble. INSTRUCTION: CO2 source - compensating valve - solenoid valve - air tube bubbler - bubble diffuser - fish tank, pay attention to the direction of CO2 flow when installing. WITH CHECK VALVE: With check valve function to prevent backflow when pressure changes, which can protect the water pressure gauge and CO2 cylinder. FREE WARRANTY: Any problem, please contact our store without hesitation. Honor to serve you! 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 to the trim valve, G1 / 8 interface only Double Head: Connected to the 6 * 4mm air pipe (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. Package Information: Package Size: 10 * 2.5 * 2.5cm Package Weight: 30g Plastic Packaging