New generation of ultra-light gear.  These sacks weigh next to nothing, but they are hand-made out of strongest fabric on Earth and will keep your belongings completely dry. 

Technical specifications: 

Volume: .... 3.8L / 9.5 L / 15 L
Dimensions (H/W)  S: 11"x8.5",  M: 16"x12",  L: 50"x35" 
Weight:   0.60 oz / 0.92 oz / 1.05 oz    
Dyneema Composite Fabric  S:  0.8 oz /yd2,  M: 1.0 oz/yd2   L: 1.0 oz/yd2 

100% Waterproof,  YKK buckles