AQUARIUM AIR STONE 12.7cm / 5"- airstone diffuses Bubble wall for 4/6mm air tube Permeable Flexible Air Stones are a great way to aerate your growing system. 1. Aquarium Air Curtain suitable to be used for decoration and Oxygen supply in all kinds of aquariums. 2. It's bubble disperse equally and supply is excellent. creates an uninterrupted flow of bubbles. 3. Can help your aquarium by providing water movement and aeration. 4. This Aquarium Bubble Wall is suitable for fresh or salt water.