Sea to Summit Clear Stopper Dry Bag nylon Fully welded clear TPU for visibility 210D TPU-laminated nylon fabric in four colors with liter size for easy ID Durable & smooth water shedding exterior Waterproof TPU roll top closure does not wick moisture All welded construction for permanently sealed seams As an airproof barrier in our Air-Sprung Cell and Self-Inflating  mats. Here it is used in a liquid-extruded format  the TPU bonds to the  face fabric for the highest possible level of reliability. As a waterproof barrier in our Accessory Guide Cases and Map Cases;  and in several models of our Dry Sacks. Here it is used in a film  format, where its superior flexibility (even in cold weather) and  waterproofness are key. As a waterproof barrier in the Nylon Folding Bucket. This particular film is also food grade  ideal for water storage. As a transparent window in View Dry Sacks and Travelling Light products  allowing you (and TSA inspectors) to see the contents.