These waterproof stuff sacks are so light that Granite Gear had to bust out the umlauts to adequately convey how little they weigh. Made of Cubic Tech Flexible Fiber Film (CTF3), almost all of the weight of these sacks is in the plastic buckle. A 10-liter CTF3 sack weighs less than some 1-liter sacks made of conventional nylon. Best of all, the CTF3 material is extremely strong for its weight; a popular demonstration for our in-store customers has us trapping air inside these sacks and then standing on them while inflated. They"re tougher than you would think!