I've been using this top as my baselayer for a couple years now. Like all Icebreaker products, the merino wool is that of extremely high quality. It breathes extremely well, is warm, and doesn't garner any gnarly smell. Ive gone weeks without washing mine. The fit on this piece is pretty good, although when using the thumbholes the sleeves are a little stretched out, so longer sleeves would be appreciated. Overall: does what any good baselayer should do- makes you forget you're wearing it.