This Air Stone is made of sandstone material and is durable. Designed to add oxygen and circulating nutrients to your hydroponic growth system or aquarium. It is suitable for hydroponic systems, ponds, aquariums, fish tanks and other systems. Features -Color:Light Grey -Material:Sandstone -Size:4.00X4.00X1.50cm/1.57X1.57X0.59in -Increase air circulation and oxygenate the water, which is beneficial to pet fish. -This aquarium bubble stone is used to increase the oxygen in the fish tank. It is a good accessory for your fish tank. -A great way to add oxygen to your fish tank, aquarium, hydroponics and circulatory system. -The bubbles are uniform, small and dense, and the oxygenation effect is good, which is easy to use. -The air stones produce a good amount of dense bubbles. A great way to increase oxygen solubility in your aquarium and enliven the . Package list: 6 × air stones