Nathan NS5025 Hpl Hydaration Running Backpack with 2L Bladder 90% nylon / 10% polyester Imported Nathan's iconic featherweight hydration vest comes with a light and breathable perforated back panel to make your next 100-miler a breeze. Patented 3-way Propulsion Harness stabilizes side-to-side/up-down movement of bladder and other contents for a bounc