The Patagonia R2 vest is the perfect fleece vest for the outdoors. It provides an excellent warmth to weight ratio. It is both breathable and warm. Its directional knit wicks moisture and speeds drying over time. The collar and chin flap is lined with polartec power stretch fabric that provides soft comfortable material that is excellent to wear. The body of the vest is made with Thermal Pro 98% mostly recycled polyester and 2% spandex. The side panels are Polartec power stretch material for freedom of movement and comfort. This jacket weighs in at 243 grams. Did I mention this vest looks sweet?