This item is a simple and practical CO2 generator system which is special designed for fish tank. It helps promote plants growing, easy and safe to set up. With pressure gauge, safe area and scale can be seen clearly. This bottle is very well suitable to be DIY CO2 system's accessory that the size fits common plastic bottle. The complete DIY CO2 kit combo for planted aquarium. Features - ColorTransparent - Material: Plastic & Glass & Ceramic. - CO2 Diffuser Size( W): Approx. 2.36 x 1.18inch / 6 x 3cm. - U Size( W .): Approx. 1.77 x 0.98 x 0.12inch / 4.5 x 2.5 x 0.3cm. - Check Value( D.): Approx. 2.05 x 0.16inch / 5.2 x 0.4cm. - Including plastic check value, U , glass CO2 Diffuser and suction cup. - Extra fine ceramic micro diffuser plate. - Check protects the gas system and air pump equipment from back-siphoning damage. - Promoting plants growing- easy to set up- - safe. Package list: 1 * CO2 Diffuser with Ceramic Disc 1 * Check Valve 1 * U 1 * Sucker