40L Nylon Rolltop BackpackHeavy duty, 700 denier nylon with Rain Defender durable water repellent and coated fabric in key wear zones Large main compartment with roll top closure that can be extended for a bigger load Dedicated side access, padded 17" laptop compartment Bottom straps with side release buckles for quickly stowing a jacket Molded back panel with channels to allow for airflow and prevent sweat buildup Coated canvas front zippered pocket with pen sleeves, mesh