Increases oxygen and lowers CO2 levels. Durable & washable. Sturdy and non-toxic material is Safe to your fish.We choose this best quality air stone that will create an abundant cascade of small to tiny bubbles rather than a limited number of larger bubbles. Can be easily driven by even Nano air pumps, suitable for aquarium, fish tank and circulation system.We respect and cherish each customer, if you have any questions whether before or after ordering, please feel free to contact us, we make every reasonable effort to supply service that satisfy your requirements.Package Including1