The Penn Plax Bendable Bubble Wall Air Diffusers are made of a pliable tube that can bend and conform to any shape. The tube is not only flexible but porous, which creates an uninterrupted flow of bubbles. The Bendable Bubble Wall is weighted, which allows it to stay in place at the bottom of your tank. Bends and conforms to any shape Extremely porous and flexible Weighted to stay in place Creates an uninterrupted flow of bubbles