SealLine BlockerLite Dry Sack Waterproof Stuff Sack (2017 Model) Waterproof strength: all seams are welded to deliver superior strength, durability, and Waterproof Protection Efficient-packing: pack tight packing system takes advantage of the flat-sided, rectangular shapes of the Blocker Dry sacks Ultralight: featherweight 20-denier silicone- and polyurethane-coated nylon delivers Waterproof Protection Secure: roll-top closure features a Grippy stiffening strip to ensure a wrinkle-free, secure Seal when closing the Dry sack Easy organization: the Blocker Dry sacks are Available in 4 Colors and 5 sizes, making it easy to organize by both color and size