User Review: Patagonia Men's Capilene 2 Lightweight Zip-Neck
Source: received it as a personal gift
This is a true classic. Warm, fitting, nice next-to-skin.
I think that every company does something especially well; this is Patagonia's strength. It's breathable, warm, strong, stretchy, comfortable and light.
This is definitely my go-to underneath a shell on a 3-season campout or winter high aerobic activities. The fit is pretty close, so I don't really like to wear it on the outside unless I'm sitting by a fire in my PJs (these) and I'm not super worried about wind.