When tackling an ultra-marathon, 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 500-milliliter 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 you as well as moving sweat away from your skin. Two energy pockets hold energy gels, and 2 secure mesh pockets hold wet socks, extra bandaids and lube, or extra food when the night grows long. 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. Motion Fit Trail system. Sensifit pack. Twin link sternum strap. 2 zippered side, 1 front zippered phone, 1 zippered back pockets. 1 chest, 1 back, 2 front hydration pockets. 1 battery, 1 back kangaroo pockets. 2 soft flasks included. Reflective details. Safety blanket included. Attached whistle.