Penn Plax Bendable Bubble Wall Air Diffuser UNINTERRUPTED FLOW OF BUBBLES: use for aerating and oxygenating your tank. PLIABLE, POROUS, AND WEIGHTED: bends and conforms to any shape and stays at the bottom of your tank. PERFECT SIZE FOR YOUR AQUARIUM: this bubble wall measures 35.5 inches long, but other sizes are available, sold separately. SHOP PENN PLAX: Penn Plax sells a wide variety of pet supplies, for animals both big and small.