Rugged Tactical Polyester. Includes: One Large Main Compartment. One Outside Pocket With Inside Mesh Accessory Pockets. Hydration Pocket With Velcro® Closure And Carrying Handle; Complete With 2.5 Liter Bladder. Modular Attachment Points On Front Face. Expandable Design And Stay-Cool Mesh Backing. Fully Adjustable Shoulder Straps. Heavy Duty Zippers And Hardware. Fully Expandable. Size: 17" X 8" X 5"