Made of high quality material, which will be durable and reliable. With the non-return function to prevent backflow when the pressure changes, and this can ensure the table of water plant and the CO2 bottle from the damage. It can count the volume of carbon dioxide and provide plants with enough carbon dioxide. Is to install and to use, a good choice to make your aquarium different. Double head and single head are available, you can choose according to your needs. Method of installation: Single head bubble counter: Remove the sealing ring and install it on the interface of the trachea, then tighten the bubble counter. Add 4/5 water into the bubble counter, then tighten the top cover. Plug the CO2 hose, then tighten the trachea attachment nut. Double Bubble Head Counter: Add 4/5 of water into the bubble counter, then tighten the top cover. Plug the CO2 pipe, then tighten the trachea fixing nut. Features: Condition: 100% Brand New Item Type: Bubble Counter Material: Aluminum Alloy 0026 & Acrylic Color: Silver Optional Type: Double Head, Single Head Double Head Size: Approx. 8.2*2cm or 3.2*0.8inch (L*D) Single Head Size: Approx. 8*2cm or 3.1*0.8inch (L*D) Package Weight: Approx. 32~34g Package Includes: 1 x Bubble Counter