The Cerium Vest W from Arc'teryx weighs little but insulates perfectly. It comes with an insulating layer made from responsibly sourced down (RDS), which is supported by synthetic insulation made from recycled polyester in areas that are sensitive to moisture, such as the shoulders. The fill power of the down is given in "cuin" (cubic inches per ounce). In the case of the vest, it is 850 cuin, which is a very high value. The higher the cuin number, the higher the fill power and therefore the greater the thermal insulation for the same weight. The outer fabric made from recycled polyamide keeps the down inside and the moisture outside thanks to the water-repellent impregnation. The Cerium Vest is cut close to the body and has three zip pockets.
