We've solved the problem of being too cold when you start running or too hot when you get going. ColdGear® Reactor actually adapts to what you're doing by dumping heat as you pick up speed.ColdGear® Reactor is intelligent insulation that adapts to your activity level for the right breathability & warmth for what you're doingEnhanced breathability helps maintain your body temperature, adapting to the weather & your level of activityLightweight quilted insulation helps keep you warm without weighing you downMaterial wicks sweat & dries really fastAnti-odor technology prevents the growth of odor-causing microbesGenerous 1⁄2 zip front for easy layeringHigh, slouch neck construction provides ultimate comfort & protectionFront kangaroo pocket with secure, zip pocket built-inThumbholes help keep sleeves secure & trap body warmthDropped, shaped hem for enhanced coverageReflective details for low-light runs100% NylonImported