This streamlined pack is an excellent day pack for anyone who is physically active or into the great outdoors. The comfortable hydration pack is contoured to fit your body and include six mesh panels on the back to allow maximum air flow to help keep you cool. The straps are padded and their are hose guides on both the left and right side. This pack includes a bladder with hose and valve, plus a 17" x 7" x 4.5" (when expanded) compartment and a big exterior pocket. Inside, there are two mesh pockets and a clip for your keys or other item.