"Have a longer journey ahead of you? The breathable Hydro Flask 14 L Down Shift Hydration Pack is equipped with a 2 liter HydraPak® IsoBound™ insulated sweat proof reservoir and Cold Flow™ System that keeps your water cold for 3+ hours. With excellent back ventilation, plenty of easy access storage and an integrated whistle in the chest strap, you'll be ready for every twist, turn, and ""let's stay a while"" views that your ride will bring."