Ultraspire 2016 Women's Astral Hydration Vest - UA044 Finally, a vest that doesnt squish the chest while providing comfortable fit and style for beautifully fit people of all sizes and shapes. Proprietary large-holed mesh, made of soft microfiber polyester for comfort and breathability. One size fits most. Breathe easier: The unique curved harness is designed eliminate the pressure of pockets, weight, bounce and excess fabric from the chest. Also provides some support when properly worn for that purpose. Only harness which will accommodate a wide range of beautiful shapes and sizes. The Max O2 Sternum attachment system with enhanced recoil provides a better range of motion, a quick in and out, and a boot hook type attachment system. Adjust once and lock down to eliminate further fuss even when taking on and off. Small internal zippered pocket for keys, lip balm or other essentials, plus large zippered main compartment. Front pockets and quick stash pockets have more stretch and capacity without added bulk or weight. Bladder hanger system: Lightweight, easy and fast method of attaching bladder inside pack. No struggling to detach or reattach bladder. Great for aid stations and lightning fast refills. Includes a 2L bladder, and a Plug-n-Play Connector.