Keeping feet warm in the backcountry during winter, and protecting against frostbite, is one of our biggest concerns, and these “Hot Socks” do just that. Put them on immediately after shoes come off, and they’ll keep your feet warm and cozy. It works better than letting your feet cool down and then trying to re-warm them forever in the sleeping bag. Primaloft insulation on the inside and water repellant microfiber on the outside keep them dry too.