Level 2 polywoven dunnage air bags can be used in virtually all types of shipping containers, either piggyback (container or trailer on the railroad) or for ocean transport. These poly bags are lightweight and easy to handle, but are capable of withstanding tons of pressure to protect against shifting, shock, and vibration. Level 2 polywoven bags are composed of an air-tight polyethylene inner layer with a reusable valve and a strong, elastic polypropylene outer layer. The bags are flexible, which allows you to fill up every shape and random space without damaging the product.