Features: brand new and high quality High CO2 Dissolution Rate: 80% dissolution rate, optimizes the CO2 entering aquarium, and increasing the saturation of CO2 in the aquarium ecosystem. Premium Glass Quality: Eco-friendly and high quality glass, easy for cleaning and maintenance when needed. Beautiful in Appearance - Transparent glass perfectly match with your for tank. Convenient Installation: Installed inline in the outflow tubing of the aquarium filter, or below the aquarium or mounted to the outside of your aquarium glass. Size: We offer 2 sizes, with OD 13mm, 17mm separately. Fits canister filter tubing size 12/15mm (3/4'' inside diameter), 16/22mm (5/8'' inside diameter) separately. Specifications: Material: Glass Color: Transparent Size: Fit for 12/16mm(1/2" ID) Tubing S-13mm Height 13.5cm/5.3in L-17mm Height 14cm/5.5in Weight: Approx.160g Package Includes: 1 Piece Glass Inline CO2 Diffuser Including 2 Pieces Suction Cups (13mm/17mm) note: 1.Please allow 0-1cm error due to manual measurement. pls make sure you do not mind before you bid. 2.Due to the difference between different monitors, the picture may not reflect the actual color of the item. Thank you!