Nathan VaporCloud Race Vest Dual stabilization System compresses bladder and load,Insulated bladder pocket to Block transfer of body heat to Liquid contents Multiple zippered compartments and stretch mesh stash pockets for organization and increased capacity,Side stretch mesh zip pockets hold up to 75 liters and a hidden internal back pocket holds ice pack Load lifters keeps bag contents up and close to the body and the rear external shock cord increases capacity This product is intended to be close-fitting for the best stability and running performance. If your measurements are close to the maximum chest size, we recommend to size up for the flexibility and comfort Kindly refer to 4th Image for Sizing details