When tackling an ultramarathon, the Salomon Advanced Skin Lab Hydro Skin3 12 Pack Set will have your back throughout every last grueling mile. Ultra stable, this hydration vest comes ready to wear with two 500ml flasks, emergency whistle, and safety blanket. The BPA, phthalate, and PVC flasks hold a full liter of life sustaining fluids when you're far from an aid station. When you happen upon a flat stretch of trail, the Skin Lab bag holds tight to your poles to give you arms a much needed break. The soft and stretchy fabrics help this hydration vest move with you as well and also wicks moisture away from your skin. Two energy pockets hold energy gels, and 2 secure mesh pockets hold wet socks, extra bandages, lube, or extra food. An additional bladder sleeve makes packing additional water an option, and the twin link cross body straps stabilize the pack to avoid unnecessary bouncing when you're running over rubble.