【Specification】Please pay attention to choosing the appropriate size when you buy. black 13: 13cm/5.1 inch, The air stone fits for 4mm inner diameter tube; Air Stone Disk needs to be used with an air pump to create a bubble effect and create a lively and interesting underwater landscape. The ASIN of the air pump (B07WP4MKHQ). 【Durable】The bubble plate with high temperature made and the fine bubbles can increase oxygen levels, lower CO2 and raise PH, it also can be easily washed for re-use. 【High Material】The airstone disk uses finely compressed material and the bubble is small and bubble is concentrated at one surface. 【Adjustable Atmospheric Plate】The bubble size can be adjusted, the smaller the gas volume, the smaller the bubble produced. Please soak in the fish tank for two hours before use, the effect will be better. If the water depth exceeds 40cm, the power of the air pump can be appropriately increased. 【Application】 Aquarium Air Stone ideal for freshwater, saltwater aquariums,