Whether you're putting up your tent or kicking back by the campfire, this durable and highly packable jacket will make sure you stay toasty-warm around the clock. The new bottleneck quilting pattern and ultralight ThermoBall(TM) insulation eliminate cold spots and provide an excellent warmth-to-weight ratio.Developed in partnership with Primaloft, 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.