During a two-night hut trip in Colorado’s Never Summer Mountains, our tester put these booties through the wringer. While stargazing in 14° F temperatures, his feet were almost too hot, thanks to a generous amount of 800-fill down. A non-slip rubber outsole and DWR-treated nylon face fabric kept the down dry and intact, and a cinch on the upper cuff sealed out even 17 inches of fluffy Colorado powder while trudging to the outhouse. And with all that, the booties packed flat in his backpack, hardly taking up more space than a thin paperback book. $100; 6 oz; XS-XL