Sea to Summit Ultra-SIL Compression Dry Sack nylon 30D Diamond Ripstop Siliconized Cordura 3 straps for even compression Extra long straps so these sacks can really be filled to capacity Bar tack reinforced stress points Pull handle on the bottom water-resistant products (such as the Ultra-Sil Stuff Sacks) are siliconized on both sides for ultimate packability waterproof products (such as the UltraSil Dry Sack are) siliconized on the outside and PU-coated on the inside to allow seam taping. In the base of our best-selling eVent Compression Dry Sacks, Evac Dry Sacks and Ultra-Sil Compression Dry Sacks. In this application, the laminate utilizes a 40 denier nylon face fabric: the material allows air to be pushed out of the dry sack/compression dry sack but prevents water from entering. This means you can compress the air out of a dry sack without needing a purge valve!. In the upper section of our Quagmire and Alpine Gaiters. In this application, the laminate utilizes a 70 denier nylon face fabric. The material allows perspiration to pass through easily but prevents external water from entering. The result: waterproof protection and superior breathability!