The Filson Ultralight vest is a lightweight packable layer that provides warmth, wet or dry. It blocks the wind, adds warmth worn alone, and is low-bulk for wearing under a rain jacket. The 1.5-oz. Cordura nylon shell fabric has ripstop reinforcing for strength that belies its weight. A second layer over the shoulders adds durability and weather resistance. This ultralight fabric is descended from the material that was developed for parachutes during WWII and has revolutionized outdoor gear ever since. The 60g PrimaLoft Gold insulation was engineered to closely mimic the softness and compressibility of goose down, while retaining 98% of its insulating ability when wet.