Sea to Summit Ultra-Sil® Dry Sacks are more than 50% lighter than our super popular Lightweight Dry Sacks. They\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\'re made of Siliconized Cordura®, which is one of the lightest and toughest waterproof nylon fabrics available. Now you don\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\'t have to choose between keeping your gear dry and keeping it light.