The vacuum bag is similar to a bean bag but with a twist. The bag comes complete with a pipe and hand pump, you rest the camera/lens in the bag and shape the bag to suit then you pumpout all the air in the bag. In the process the bag becomes solid still in your chosen shape. Afterwards simply let the air back in to reshape. The benefit of this is that the bag is easy to manipulate into shape in the firstplace and then gives firm support once pumped out.