"Made from premium resin and plastic, durable, non-toxic and pollution-free. Absolutely safe for the fish you beloved. Great-looking ornament Ideal for various fish tank and safe for fresh and salt water, either your freshwater fish or saltwater fish can play with their new toy Real motion air-driven ornaments provide entertaining action while aerating your tank. When the diver floats the treasure chest will open and closes to revealing the treasure inside, more vivid and active Requires an air pump (Not Included) & 3/16"" tubing (Not Included) and an air valve to control the flow of the air to the chest, then you can adjust the frequency in which the lid opens Note: Please notice the measurement in the fifth image. This item may be not as large as you think"