Layer the Arc'teryx Mens' Cerium LT Hooded Down Jacket under your shell when you head out for a backcountry tour on a crisp, cold morning, or use it as an outer layer for chilly fall hikes. The combination of 850-fill goose down and strategically placed Coreloft insulation keeps you warm during bone-chilling days in the backcountry. While Coreloft insulation does resist moisture better than down, and an ominous drizzle won't leave you a cold, soaking mess, it's best to pair this with a waterproof shell if you know wet weather is coming. This superlight hooded jacket comes with its own stuff sack so you can easily bring it along on your next ski tour.