The Arc'teryx Men's Atom LT Jacket is a mid layer jacket for cold weather activities such as skiing, climbing, and hiking. The Atom LT is packed with CoreLoft synthetic Insulation that boosts warmth and dries quickly in the event it gets wet. Tinthan fabric protects the insulation from the outer elements, a 100% nylon material that is lightweight and abrasion resistant. The durable, water-repellent coating on the outside helps deter water from soaking in. The side panels are Polartec Power Stretch for movement and breathability during aerobic activities. At 11.1 ounces, it packs down small and won't weigh your backpack down, so you're always ready for unexpected cold weather.