Description: High-grade polished stainless steel CO2 diffuser, durable as well as elegant, adding a beautiful scenery to your aquarium. 2 sizes bottom diameter: 3.6cm/1.41" and 2.4cm/0.94", 5 length available (20cm/7.87", 25cm/9.8", 30cm/11.8", 35cm/13.8", 40cm/15.7") to satisfy your needs. Helps to ensure plants receive proper amounts of CO2, improve the growth and health of your plants with sufficient CO2 supply. The CO2 diffuser disc must be screwed as tight as possible when installation. Notice: The CO2 diffuser may release big CO2 bubbles during its first 1-3 days of usage. When ceramic disc becomes saturated with water, it will then release fine CO2 bubbles, this is normal and may take up to 3 days. Specification: Material: 304 Stainless Steel CO2 Diffuser Bottom Diameter: 3.6 cm/1.41 inch; 2.4cm/0.94inch CO2 Diffuser Length: 20cm/7.87inch; 25cm/9.8inch, 30cm/11.8inch, 35cm/13.8inch, 40cm/15.7inch Package Includes: 1 Piece CO2 Diffuser Note: Since the size above is measured by hand, the size of the actual item could be slightly different from the the size above. Due to the lighting effects, monitor settings,etc.There could be some slight difference in the color of the pictures and the actual item.