I used it once, but haven't had a chance to use it since, so I'm selling it. This is the "Nuptse Muffler" from THE NORTH FACE. It uses 50-denier recycled nylon, and the insulation is high-quality 650-fill-power down. It's lightweight yet voluminous, providing excellent warmth. One end has a hole, and you can easily put it on by inserting the other end. The opposite side is pocketable, making it compact for carrying.