Product description Size: 4.5mm Color: black material: plastic Package content: 10pcs one-way valve to stop water 1.【Improve CO2 Dissolution】: Double seal ring improves CO2 dissolution efficiency. 2.【Non Slip】: The suction cup makes the bubble stone firmly adhere to the water tank, not easy to slip. 3.【Applicable For】: Suitable for families, office fish tanks, ponds, aquariums. 4.【Replaceable Disc Oxygen Bubbler】: The material is sturdy and durable. It can be used for a long time and has better dissolved oxygen effect. When the bubble burst into the water, the sound is super quiet. 5.【Produce Bubbles】: A large number of thin bubbles are generated in the fish tank and dazzle.