WINTER HYDRATION BACKPACK WITH FOR CROSS-COUNTRY SKIING AND TRAIL RUNNING The NORDIC 4 is a slim and fast run/ski hydration pack for developed for racing and small adventures when XC-skiing, Running or Mountain biking. The pack deliverers 4 liters of storage, including a 2.0L hydration bladder and our revolutionary Thermo Cell insulation technology that eliminates freezing of the drink tube and bite valve even in the most extreme weather conditions.