Down with down! This season, we're stuffing our parkas with eco-friendly Primaloft, a breathable, lightweight but still very warm filling originally developed for the U.S. Army. The result? An un-bulky layer that's perfect for those blustery winter days. (This one also features tons of supersmart details, like a water-repellent exterior, thumb-holes in the cuffs, snap-close straps for their mittens, and a removable faux-fur hood.)