As light and compressible as functionally possible, the Cerium SL down vest weighs a scant 125g (4.4 oz) but delivers exceptional warmth for its weight. The 850 fill power goose down’s warmth to weight ratio is outstanding, and the tear-resistant, wind resistant Arato™ 7 nylon shell is exceedingly lightweight. It primarily functions as a mid layer, but its efficient warmth and packability makes it an effective standalone for rest breaks, evenings at camp, or emergency bivvies.