Mission Workshop R6 Arkiv 20L. Rail system modular backpack. The pack can be used in either "roll-top" mode, or in a traditional "flap-down" configuration, has one external zippered pocket for items like a phone or passport, and one interior zippered pocket that is ideal for documents and fits up to a 15" laptop. The Arkiv backpacks feature multiple weatherproof compartments, urethane coated YKK zippers, waterproof materials, and an internal frame sheet. External dimensions : 12" x 18" x 5". Internal Volume : 1,250 cu.in. (20 Liters), Weight (Empty): 3 lbs. (1.36 kg). Mark on inside flap.