Feature: 1. EFFICIENT DESIGN: Provides a stable and reliable supply of CO2, improving the CO2 content of the water to the desired level and promoting the growth of water plants. 2. SAFE AND RELIABLE: The outer tank CO2 diffuser ensures an even and stable supply of CO2, which will not harm fish and guard the aquarium ecosystem. 3. EASY TO INSTALL: External aquarium CO2 atomizer is easy to operate, easy to install and adjust, suitable for various 12mm fish tank sizes, user friendly operation. 4. ENHANCE FISH HEALTH: By adjusting the carbon dioxide concentration in the water, it provides the ideal environment needed by fish, enhances their immunity and prevents diseases. 5. STABLE AND DURABLE: The aquarium CO2 diffuser is made of durable materials to ensure long lasting use of the product, easy to maintain and use. Specification: Item Type: External Aquarium CO2 Diffuser Material: Plastic Diameter of Connecting Pipe: Outer Diameter: Approx. 16mm / 0.63in, Inner Diameter: Approx. 12mm / 0.47in. Package List: 1 x External Aquarium CO2 Diffuser2 x Refining Accessories Note: Manual measurement, please allow some errors.