can prevent the backflow when the pressure changes, and this can ensure the water pressure gauge and CO2 bottle from damage. East to install and use, a good choice to make your fish tank different. It can count the volume of carbon dioxide and supply the plants with enough carbon dioxide. VISIBLE CO2 OUTPUT: The output of carbon dioxide can be seen clearly, so that better supply sufficient CO2 for water plants.SUITABLE FOR: G1/8 interface trim valve fits for the single head solenoid valve. If not the G1/8 interface, fits for the 4*6mm air pipe (inner diameter 4mm and outer diameter 6mm). DURABLE AND EASY TO INSTALL: Be made of aluminum alloy material, b and sturdy. Also, easy to install and disassemble.INSTRUCTION: CO2 source-trim valve-solenoid valve- bubbler counter-air tube-bubble diffuser-fish tank, pay attention to the CO2 flow direction during installation.WITH CHECK VALVE: With non-return function to prevent the backflow when the pressure changes, and this can ensure the water pressure gauge and CO2 bottle from damage.WORRY FREE WARRANTY: Any problem, please contact our store without hesitation. Honor to serve you!Specification: Name: Bubble counter with check valveColor: Silver+transparentMain material: Aluminum alloy+acrylicOptional type: Single head/double headSingle head: Can connect to the trim valve, G1/8 interface onlyDouble head: Connect to the 6*4mm(inner diameter 4mm,outer diameter 6mm) air pipeSize: Single head: 20*80mmDouble head: 20*89mmNote:In the lush water tank, it is recommended to play 2-3 CO2 bubbles in 1 second.Package Information:Package size: 10*2.5*2.5cmPackage weight: 40gPlastic PackagingPackage List:1* Bubble counter with check valve2* Sealed tache