Bubble-Wall&Atilde;&sbquo;&Acirc; Bendable Air Diffusers for Aquariums by Penn-Plax (23 1/2") Bendable Bubble Wall Air Diffusers are made of a pliable tube which can bend and conform to any shape. The Bendable Bubble Wall is weighted which allows it to stays in place at the bottom of your tank. The extremely porous and flexible tube creates an uninterrupted flow of bubbles. Weight: 0.2300 lbs. Cubes: 0.0005.