Check the listing for details. 20 Pcs Air Diffuser Mineral Bubble Hydroponic Oxygen Stone Aquarium Fish Tank. Condition: New. Listed at 15.50 USD. PACK OF 20 - FREE SHIPPING - Air Diffuser Mineral Bubble Hydroponic Oxygen Stone Aquarium Fish Tank This item is a high-temperature sintered air stone. With its delicate surface and uniform air outlets, it effectively transports oxygen to fish and other aquatic life, making it suitable for use in fish tanks, ponds, aquariums, and other environments. Additionally, it is useful for purification, filtration, water ozone sterilization, and aeration. Features - Color: As shown in the picture.- Material: Sand.- Size: 40 * 15 * 15 mm (L*W*H).- Easy to use: Connect to the air pump and put it into the water, helping the air pump to pump oxygen into the water.- and hard material, good for long-term use and safe for living things.- Can be washed repeatedly.- Beautiful air bubbles add beautiful scenery to the aquarium and fish tank.