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 insure the water plant table and the CO2 cylinder from damage. It can count the volume of carbon dioxide and provide plants with enough carbon dioxide. Is to set up and use, a good choice to make your aquarium different. Double head and single head are available, you can choose according to your requirement. Features: Condition: 100% brand new Item type: Bubble counter Material: Aluminum alloy 0026 amp; 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 The Package Includes: 1 x Bubble Counter