Features: 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. Durable, washable and sintered by high temperature. Creates bubbles in fish for tank while attached to an air pump(air pump is not included). Creates water currents and dazzling underwater scenes. Perfect accessories for better life Help to keep fish healthy and adds for extra beauty to the aquarium Specifications: Material: Mineral stone+Plastic Color: Blue Size: 6.5x4cm Quantity: 1 Pc Package Includes: 1 Pc x Air Bubble Stone note: 1.Transition: 1cm=10mm=0.39inch 2.Please allow 0-3cm error due to manual measurement. pls make sure you do not mind before you bid. 3.Due to the difference between different monitors, the picture may not reflect the actual color of the item. Thank you!