Refined over the years our U.L. Thermawrap series has become a mainstay for discerning outdoors people world wide. The concept: simple, lightweight, compressible, and thermaly efficient when wet. We utilize Exceloft, an extremely durable insulation that dries quickly and retains less than 1% of its weight in water. This innovative blend of materials and design provides the warmth that is critical when mixed conditions prevail. Welcome to the future of ultra light synthetic insulation!