Features: Bubble stone Commonly known as diffuser stone (Sha Tau), a durable, good aeration, filtration, and widely used:A sewage treatment plants for aeration and stirring to prevent large particles of sediment deposition, and removal of some organic matter. Aquarium (fish farms) eutrophic water body increase oxygen into the environment, bio-farming increase oxygen Live fish and seafood transport increase oxygen. Aquarium (purifiers) purification, filtration and water quality ozone sterilization and aeration. Other required air diffusion process uses. Specifications: Material: Ore Size: app.4cmx1.2cm/1.57''x0.47'' Color: Random delivery (If you buy more than one,the color you received may be the same color or different colors) Quantity: 10pcs Package Includes: 10Pcs x Air Stone (without retail package) note: 1.Please allow 1-3cm error due to manual measurement. pls make sure you do not mind before you bid. 2.Due to the difference between different monitors, the picture may not reflect the actual color of the item. Thank you!