Layering is king; especially when those winter hikes are involved and you're going to make sure that you have the right base layer to keep you going and keep you warm. This section contains the heavyweight champions, these Cap 4 undergarments can be worn as a base layer (as intended) in order to keep you super dry and super warm or alternatively are thick enough to be worn over something a little lighter. Either way, you can be sure that any cold air you're exposed to will not be getting inside.
Patagonia Men's Capilene Thermal Weight Zip-Neck Top 43657
Patagonia Men's Capilene Thermal Weight Long Underwear Bottoms 43687