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Updated with streamlined baffles contoured to fit your body, our PrimaLoft® ThermoBall™ jacket offers ultralight, highly compressible synthetic insulation to keep you warm in a variety of winter conditions. Our new insulation technology features round ThermoBall™ clusters that trap and retain heat to achieve phenomenal warmth in cold, wet weather. Wear or pack this ultralight jacket for reliable thermal insulation while winter camping in the backcountry.
Developed in partnership with Primaoft, Inc., ThermoBall is a revolution in insulation technology. Unlike traditional continuous-filament synthetic insulation, the small, round PrimaLoft synthetic-fiber clusters closely mimic down clusters, trapping heat within small air pockets to retain warmth. Independent clo testing by Kansas State University has shown that ThermoBall has warmth equivalent to 600 fill goose down. As a result, ThermoBall can offer the lightweight warmth and compressibility of down with the wet-weather insulating performance of synthetic insulation.