Check the listing for details. 4Pcs 12.5" Long Stone Air Release Dome Diffuser Oxygen Aquarium. Color: Green, Condition: New. Listed at 19.75 USD. Description:Fit for freshwater, saltwater aquarium and hydroponic use.Widely used to increase the dissolved oxygen level in the aquarium.Air stones allow the aquarium to create beautiful walls of bubbles that not only look good, but also help aerate and circulate the water. Instantly create a great deal of tiny bubbles that your fish will love.Creating a dramatic and funning mist of healthful bubbles in your aquarium.Evenly distributes fine bubbles through a super-porous, non-clogging wand.The bubble wall air diffuser makes a great addition to any aquarium and will add great movement to your tank. Note: The airstone need to be connected with your pump(Not Included).Please soak it in water for at least 15 minutes before use.