Everyone knows that square is the more efficient shape for packing compared to the space-squandering circle, so Granite Gear designed their Air Compressor Sack in a Bloc. Not only does that save space by eliminating dead areas but allows stable stacking and a tidy fit in the corners of your pack. Tough, translucent sil-nylon Cordura construction lets you see what you've stuffed and organize with ease. Lighter than webbing system, the micro-cord and Poplock keep things lean, tight, and secure.