Keep the Lassen Polartec® Beanie handy for all your heart-racing adventures when temps start plunging. Perfect for frigid trail runs or winter marathon training sessions, the lightweight Polartec Power Grid™ fleece traps heat and wicks sweat during long, fast-paced spells out in the cold. The low-profile beanie is so thin it even doubles as a helmet liner for freezing days of swinging ice axes and exploring backcountry powder.