The DrySack by Granite Gear. Drysacks Are ultralight waterproof roll closure bulk reducing sacks that Are ideally shaped for easy and efficient packing. The extremely waterproof non-pvc fabric is lightweight and durable. Once compressed and sealed they maintain their wonderful block shape that is ideal for stacking in your pack. We also added an arched rolling stay that helps keep the top of the sack open while loading and shapes an easy to grab handle when sealed. The ultimate cure for compression. Reduce weight and bulk!. Features of the Granite Gear Drysack 70 D Nylon Ripstop for greater abrasion resistance Waterproof rolltop closure Lightweight and PVC free Hot - Weld taped seams Rolling stay helps for holding sack open while loading Space saving shape.