This professional air bubble stone, made of , is durable and practical with . It is a great way to add oxygen to your aquarium, fish tank, hydroponic and circulation system. Great for fish tank and aquarium use. It will be the for you. Feature - Brand: POPETPOP. - ColorGrey - Material: Sandstone. - Size: 2.00X2.00X3.50cm/0.79X0.79X1.38inch. - Durable, great for home, office fish tank, aquarium and hydroponics nutrient tanks. - The surface is frosted, delicate and smooth, and the bubble output is more even, good to the growth of aquatic animals. - Maximizes the outlet area of the air stone to provide a larger area for bubbles. - Add beauty to your display aquarium with this round air stone to create micro bubbles. - Produce fine air bubble that increase oxygen levels and circulate nutrition. Package list: 12 x POPETPOP Air Stones