Oksale&reg; 1Pc 2Pcs 3Pcs Air Bubble Stone Aerator Aquarium Fish Tank Pump Hydroponic Oxygen 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, different from other air stones Creates bubbles in fish tank while attached to an air pump Suitable for inner diameter 4mm soft tube, If you need, please contact us