Features: 1.Adopt sand stone, after high temperature agglomeration, good gas diffusivity, good filter, strong ozone resistance, corrosion resistance. 2.Can increase oxygen content, reduce carbon dioxide and increase pH. 3.Air Stone is an important tool for aquarium fish tanks to maintain the breathing process of fish. 4.Durable air stone and can be reused and washed repeatedly. 5.Suitable for fish tank and aquarium oxygen pump. Specification: Item type: Air Stone Material: sand stone Weight: Approx. 260g Color: blue Ball diameter: Approx. 2-3cm/0.8-1.2in Products are widely used in: 1. The sewage treatment plant aerates oxygenation and agitation to prevent sedimentation of large particles and remove some organic matter. 2. Aquaculture pond (aquaculture farms) increase oxygen in the environment's eutrophic waters and increase oxygen in biological cultures. 3. Live fish and seafood transport oxygen. 4. Aquarium (purifier) purification, filtration and ozone sterilization and aeration. 5. Other process uses that require diffusion of air. PackageList: 20 x Air stone Note： 1. Soak in water for 15 minutes before use. 2. If the dirt is clogged and the air bubbles are reduced during long-term use, take it out of the aquarium and wash it repeatedly. 3. Air stone can be reused.