Full waterproof protection with a simple roll-top closure, our Blocker Dry Sack provides resourceful adventurers an efficient-packing shape to optimally organize and protect essential clothing and gear inside a pack. Versatile materials: Lightweight 70D polyurethane-coated nylon materials are a tougher, more resilient cousin to the ultralight BlockerLite materials. More durable and versatile, these materials are great for all-around use with confident waterproof protection. Waterproof closure: Roll-top closure features a wrinkle-free stiffening strip to ensure a secure seal when closing the dry sack. Durable construction: Fully welded seams result in stronger and more durably protective construction compared to sewn-and-taped seams. Efficient-Packing: PackTight(TM) packing system sacks feature flat-sided, rectangular shapes that nestle closely together, packing 20% more efficiently than rounded sacks for easy, space-saving organization.