Here's what other sites are saying:
Nathan's Endurance Hydration Vest rises above the rest by offering a hydration solution that's just as comfortable during your training runs as it is on race days. Streamline and lightweight, this vest includes a two-liter water bladder to keep you hydrated and multiple storage options for nutrition and layering. Mesh shoulder straps allow excess heat to vent away from your body, soft perimeter binding eliminates the opportunity for the vest edges to chafe against your skin, and four adjustment straps give you the power to achieve the perfect, bounce-free fit. This vest takes the stress out of carrying your hydration when you're running thirty miles of trail non-stop.