Smartly equipped for frigid alpine environments, the Arc'teryx Women's Cerium LT Down Jacket keeps you toasty while you're pushing for the summit in single-digit temperatures. The Cerium LT's lightweight design (it's only 8. 3-ounces!) makes it well-suited for ski tours where pack space is crucial. High-loft 850-fill European goose down is placed throughout the body for balmy heat retention, and it's combined with Coreloft synthetic fibers in zones prone to moisture-retention, such as the underarms, collar, hemline, and cuffs. This combination of down and synthetic insulation is truly the best of both worlds, working to keep you pleasantly warm through demanding alpine conditions and active wintertime use. Since it's predominately down, the Cerium LT is primarily intended as a warm midlayer underneath your waterproof shell. However, it's also a stellar standalone piece in cold, dry environments when heavy rain and snow aren't an issue.