Buy one get four free accessories】The air stone set includes a 2-inch nano air disc stone, 1 control valve, 1 one-way valve, and 2 meters of tubing.Super High Dissolved Oxygen】This upgraded air stone releases smaller, denser and more uniform bubbles, doubling the amount of dissolved oxygen in the water.Produces small and dense bubbles】The bubbles released are smaller, denser and smoother than others, and when the bubbles burst into the water, the sound is smaller. It creates a fogging effect and bubble bundles to make your aquarium look like a wonderland.Weighs enough to sink]. 5.2 oz/150g, it can easily be placed on the bottom without suction cups. The air diffuser area is 2 inches in diameter, excluding the plastic rim. Suitable for fresh and salt waterDriven by 2W or greater wattage air pump】2 inch air diffuser is compatible with 4mm air tube, output air flow is 1L/Min. Please note that the deeper you put the air stone on the bottom of the water, you may need to use a larger