Scuba-Diver Underwater Elastic Tank Banger-Knocker / Safety Signaling Communication Device. This simple but innovative scuba safety tool ensures divers can effectively communicate underwater.Connected to a diver by a strong and stretchy elastic band, allowing it to be easily installed and adaptable to all tank sizes.Simply pull and pop against your tank to alert other divers in the area, or to get the attention of your dive buddy.Specs:Crafted with durable abs plastic, stainless steel, and hd elastic materials.The banger's distinct sound and simplicity make it a must-have for underwater safety, communication, navigation, and sharing thrilling encounters with fellow divers.Great for divers of all experience levels. A must have for safety!