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.