Our warmest fleece made to enhance mobility in frigid temperatures and prevent windchill nightmares. Now with a toastier fabric package - variegated fiber R2® on the inside and full-loft R2® on the outside sandwiching a windproof laminate - our stretchy R4 excels alone or under a shell. Its lack of shoulder seams allows pack-wearing comfort and the high-placed handwarmer pockets stay clear of a harness. Made in USA. Regulator® SystemRegulator is an integrated system (base insulation shell) that works in unison to keep you dryer and more comfortable over a wider range of conditions than a traditional waterproof layering system.