“Suction cups are made of soft plastic clear material which will stay firmly either outside or inside the tank with water. A necessity for setting up an air pump.^ Easy to use Come in handy Durable & Reusable Strong suction force^ Great for 3/16"” ID or 1/4"" ID aquarium airline tubing. Each suction comes with one clip. If they come apart, just push the clip back into the suction cup. ^ Notes: Please soak them in hot water if they get warped, they will turn white after a while use in water which not affect usage. ^ Make sure the suction cup and the surface you adhere to is clean and free from debris before using."
