Featuring a waterproof valve that purges trapped air, the versatile Blocker PurgeAir Dry Sack resists ballooning to help maximize use of space within a pack or bag. Plus, the fully waterproof construction ensures essential contents are protected. . . . 70D polyurethane-coated nylon. . Lightweight 70D polyurethane-coated nylon materials are tough and resilient. More durable and versatile, these materials are great for all-around use with confident waterproof protection.. . Unique and waterproof PurgeAir valve vents trapped air, helping the sack compress further after being sealed, and is both more durable and more reliably waterproof than waterproof/breathable fabric membranes.. . Roll-top closure features a wrinkle-free stiffening strip to ensure a secure seal when closing the dry sack.. . Fully welded seams result in stronger and more durably protective construction compared to sewn-and-taped seams.. . PackTight 40818097700 32966500006 9770