Penn-Plax Action Air Skeleton on Wheel Ornaments bring animation, charm, and life to your underwater world while aerating your tank. The skeleton steers the wheel with help from the bubbles that come out from the bottom of the ornament, providing your tank with much needed air. Simply connect the ornament to a standard 3/16 airline from your air pump (not included) and watch as the steady stream of bubbles lets your skeleton steer. Use your pressure control valve (not included) to adjust the motion and volume of air, if desired. Made from a durable plastic resin that is safe for your freshwater or saltwater / marine aquarium. Fun to watch and entertaining for all, Action Air ornaments fit in almost any tank and come in a variety of styles and sizes so you can continue to add to and customize your aquarium design. The Skeleton at the Wheel measures approximately 3.5”L x 2.5”W x 6”H.