The Arc'teryx Men's Cerium LT Down Jacket weighs in at just under a half pound, but still packs a wallop of warmth when you're ice climbing, backcountry skiing, or out for a hike. Arc'teryx placed 850-fill goose down through the torso and arms, and it added Coreloft synthetic insulation in locations that are likely to suffer exposure to moisture--the shoulders, collar, and along the hem. The dynamic duo of high-tenacity Arato 10 face fabric and high warmth-to-weight down insulation fights cold during those bitterly cold belays, ski transitions, or brief moments at the summit. Its trim silhouette means you can layer over the Cerium and still put your arms down comfortably by your sides. Underarm articulation gives you upper body mobility so you can plant a pole or swing an ice axe without tearing seams or exposing flank flesh. Light elastic cuffs won't pinch your wrists but will rebuke cold air attempting to slither up your arm. The included stuff sack makes the Cerium LT easy to stash in a backpack when you're ready slap skins back on your skis for another powder lap.