Its lightweight loft makes you think The North Face ThermoBall Full Zip Jacket is a down jacket, but it's actually synthetic. The Primaloft Thermoball insulation acts and even looks like down insulation, providing lofty warmth equivalent to 600 fill down. It even compresses like down jackets so you can stow it in its pocket and take it with you on backpacking or climbing excursions. But because it's synthetic, the ThermoBall stays warm even when you get wet during backcountry ski sessions through powder. The ThermoBall features a durable nylon shell that slides under other layers with ease. Its cuffs have an elastic binding to keep the sleeves from riding up your arms. A hem cinch cord tightens to prevent breezes from blowing up your body, and two hand pockets keep your hands warm when you reach the top of the mountain.