Description from website. I accidentally ordered two of these, grab this one for a deal! The Especial Series backpacks are built for the serious cyclist. Featuring premium, rugged fabrics, internal drop liners, and a flexible back panel for all day comfort. Expandable volume fits everything needed. Ripstop nylon 6.6 provides high abrasion resistance and exceptional strength to weight ratio Internal drop liner with waterproof seam tape construction Features Backbender flexible cooling panel with comfortable backpack straps Sternum strap and detachable waist strap