10/13/20cm Aquarium Air Bubble Stone Fish Tank Hydroponic Oxygen Diffuser Plate. Specifications: Practical and durable home using product. Increase oxygen levels, lower CO2 and raise ph. It is an important instrument to successfully keep aquatic fish for respiration process. Creates bubbles in fish tank while attached to an air pump. Creates water currents and dazzling underwater scenes. Easy and convenient to use, perfect accessories for better life. Before use, please immerse it in the water for 15 minutes. When the air bubbles are reduced, the stone can be taken out for washing and used repeatedly. Item Name: Air Bubble Stone Material: White Steel Jade + Silicon Carbide + Plastic Features: Lower CO2, Easy to Use, Reusable Diameter: 10cm/3.94" (Approx.) Diameter: 13cm/5.12" (Approx.) Diameter: 20cm/7.87" (Approx.) Notes: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement. Package Includes: 1 x Air Bubble Stone