Nice feel, handles moisture well, and breathes. I wear over a t shirt but under a jersey from 50s to colder. Below 50 I add a Jacket over the jersey. Not bulky, layers very well.

Size is true, not bicycling sized. Buy the same size as your t-shirt.

Con: is price very expensive for a mid-layer

Smartwool was my first none synthetic baselaye and I loved it from the first time I put it on. It was extremely warm, breathable, and comfortable. I wore it tons. However, after some use, the bottom of it pills...not a little...ALOT. I washed and hung dry it, and the pilling still happened. I asked our Smartwool rep and he said it was because it was rubbing on my pants and it was causing the pilling. Bottom line, to stop the pilling, tuck it in.

I accidentally picked this up on SaC when some overzealous clicking landed my inventory checking to a package on my doorstep. Backcountry's loss. The way I see it, if I had a warehouse full of these I would pile them up + never leave. The material is a soft, odor fighting, durable, powerhouse that acclimates + responds to your body's heat production.

The flat-locked seams are offset from the shoulders to make way for a pack + the athletic fit makes the M fit on my 5-11" 165 frame nicely.

I love this shirt. It keeps you warm but not too warm, blocks some wind, and doesn't itch. It really works. I wear them to work, on the trails as a first or second layer...anything. I would also definitely buy them at a discount if you can. Price aside, great shirt.