PVC lined construction. Four expanding compartments that provide up to 20 liters of storage. Internal dividers and zippered pockets are built in the three largest compartments. Mesh padded back panel can hold up to a 2.5 liter hydration bladder (bladder not included). Contoured shoulder straps are constructed with mesh padding and are fully adjustable. Reinforced carry handle. Mesh ventilated padded back with Velcro top closure. Shoulder straps have hard plastic D-rings for attachments. Four quick release compression straps for expansion and consolidation. Medium 2 liter external organizer pocket. Color: Dark earth. 600D polyester construction.