Sea to Summit Stopper Dry Bag nylon 210D nylon fabric with TPU laminate Durable & smooth water shedding exterior Waterproof TPU roll top closure does not wick moisture All welded construction for permanently sealed seams Features the patent pending Field Replacement Buckle with stainless steel pins 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.