Featuring a waterproof valve that purges trapped air, our 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. 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. PurgeAir(TM)-equipped: Our 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. 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.Product Specifications Features: Wrinkle-resistant, Waterproof, Roll Top Dimensions (5L): (W x L x H) 3.5 x 6.4 x 11.8 in. Dimensions (10L): (W x L x H) 4.3 x 8.2 x 14.1 in. Dimensions (15L): (W x L x H) 4.7 x 9.2 x 16.1 in. Dimensions (20L): (W x L x H) 5.5 x 10.4 x 18.8 in. Best Use: Paddling, Backpacking, Camping Weight (5L): 1.8 oz Weight (10L): 2.3 oz Weight (15L): 2.7 oz Weight (20L): 2.9 oz Stuff / Compression Sack Closure: Roll-top