The ortlieb cor13 backpacks marries a fascination with dynamic sports with high performance technology the minimalist design and weight make this a pack you can carry all day long though the cor13 has no external frame it is very comfortable backpack the padded back with ventilation channels provides efficient air circulation the anatomically contoured shoulder straps and chest strap are individually adjustable and keep the pack close to your body the 100 per cent waterproof nylon fabric