Layering is essential to ensure comfort while traveling and this midweight base layer allows you to do just that. Throw it on over a t-shirt, pair it with your puffy or outer layer and you'll be ready for any condition the day throws at you. It offers enough warmth while still being very breathable, I especially like this base layer while moving through variable temperature ranges like airport terminals or hoping in and out of shops during a cold day. REI's Midweight Half-Zip is a bargain, as other brands typically sell similar products for twice as much, albeit with more features like a chest pocket.

Tip: If you're okay with spending a little extra $ consider the softer, warmer REI Merino Midweight Base Half-Zip.