Mens Patagonia Performance T Shirt
This technical tee from Patagonia is incredibly versatile. To name a few of its features, it is quick-drying, odor resistant, stretchy, wicking, and breathable. Because of these features, you can wear this as a base-layer for the cold or as a top when it's hot.
This shirt is also responsible. It is Fair Trade sewn and made with 50-100% recycled polyester.
Available, here, in Feather Grey.