This is a top-of-the-line hybrid jacket. As usual, Arc'teryx has designed a jacket that is comfortable, has great mobility, and is loaded with features. The Atom LT has accumulated a die-hard following over the years, and it's easy to see why. It combines a high-quality Tyono shell fabric with Polartec Powerstretch side panels; this combination strikes a nice balance between warmth and breathability. With 60g/m2 of Coreloft insulation, it functions well as a mid layer for when the temps are dropping and makes for a great outer layer during aerobic activity. Arc'teryx also offers a vest version of this hoody for $175.
If you are interested in the Atom LT but don't love the high price tag, check out the Best Buy Award winning Outdoor Research Cathode Hooded Jacket. It's also a hybrid jacket and makes an excellent and less expensive alternative.