JARDLI Glass Nano CO2 Diffuser for Aquarium Plants with Suction Cup The high efficiency of diffusing carbon dioxide. Suitable for tanks below 20 US gallons, i.e. Nano tanks Atomic pores on the ceramic disc breaks down Carbon dioxide gas into tiny streams of bubbles With high surface area to volume ratio, Co2 can easily dissolve in the water Package includes: 1 x CO2 Diffuser, 1X Suction cup