Dimensions: 11.5" x 18" x 12". 600 Denier PVC lined polyester construction. Pack has four expanding compartments that provide up to 35 liters of storage. Internal dividers and zippered pockets are built in the three largest compartments. The mesh padded back panel can hold up to a 2.5 liter hydration bladder (bladder not included). Color: Tornado gray. Bulk packed.