Our warmest insulated jacket for blustery mountaineering ascents, low-temp backpacking, and anytime the weather takes a dip in degrees. Even with a heat-trapping high loft, the Phantom Alpine Down Jacket is super packable and moveable, handling long days of tight switchbacks or alpine climbs without a problem. Made to layer easily, it's also built with a burly, abrasion-resistant shell with Pertex Quantum Diamond Fuse, so if you want to rock it solo, go for it. If the weather isn't bone-chilling but simply c-o-l-d, this is your best bet to stay warm and comfortable.