You can only add so many layers before you start feeling like an inflatable Santa Claus, which is why vests exist. Stay warm this winter with the Smartwool Double Propulsion 60 Hooded Vest without adding bulk. The lightest weight SmartLoft wool insulated vest in Smartwool's line, this is great for adding that one extra layer under your shell to keep your core warm. Whether you are heading to the lifts or into the backcountry, just throw this in your bag. It also works as a great layer for those cold, but not freezing, days in the city.