Fish Tank Aquarium Air Stone Oxygen Aerator Increasing Air Bubble Pond Pump Hydroponic Oxygen Supply Stone 4/6/8/10/12 inch Features: Ozone aerated stone, bubble stone, using super hard gold steel sand, after high temperature sintering, good gas diffusion, good filterability, ozone resistance, corrosion. Increase oxygen levels, lower CO2 and raise PH, creates water currents It is an important instrument to successfully keep aquatic fish for respiration process. Durable, can be reused and washed repeatedly. Creates bubbles in fish tank while attached to an air pump(air pump and air tube is not included). Specifications: Color: As picture Material: hard gold steel sand Item Size: Approx. length 4 inch (10cm), 6 inch (15cm), 8 inch(20cm), 10 inch(25cm), 12 inch(30cm) Package include: Only 1*air bubble stone (no tubes) Suitable for inner diameter 4mm soft tube Note: -Soak in water for 15 minutes before use. -For long-term use, if there is dirt blockage, and the bubbles is reduced, please take it out of the fish tank and wash it again and again. -The air stone can be used repeatedly. -Please allow 1cm differs due to manual measurement. -Due to the different display and different light, the picture maybe a little different with the actual color of the item. Thanks for your understanding. Package Include: 2pcs Aquarium Fish Tank Air Stone Bar