The Ozone jacket liner provides warmth and comfort in extreme conditions for all-day or night, cold weather comfort (Tested in Prudhoe Bay, Alaska) Comfortable from -30 to 65 F. This unique moisture management system keeps you warm and dry without the weight and added bulk (only 1.5 pounds). Maintains your personal environment of warmth in critically cold conditions, allowing your core to stay warm even when other apparel systems fail or when wet.