Sea to Summit Ultra-Sil Dry Sacks are ideal for backpacking, bike packing, day hiking, and traveling. Made with lightweight, waterproof 30D Ultra-Sil™ fabric featuring CORDURA® yarns, they're the perfect choice for pro packing and organizing your gear inside your backpack or duffle. A no-wicking Hypalon roll-top closure and taped seams keep moisture out. The semi-translucent fabric makes it's easy to see what's in each dry bag, and the round base makes for ease of packing. Currently available in 2L Grey, 4L Grey, 8L Grey, and 13L Blue. While perfectly adequate for dry storage inside a backpack, bike bag, or duffle, this product is not intended for boating or marine use. As with many ultralight Sil products, avoid sharp or hard-edged objects and abrasive surfaces.No wonder this dry sack was the winner of the Backpacker Editors' Choice award in 2006!