Mandatory base layer as far as I'm concerned. Use one of these just about every day in the mountains. It's my security blanket. There are heavier base layers, bu I go with the multi layer approach. Works great!

Super nice fabric with smooth feel. Good warmth. Use as a base layer or solo top. BUT, found that the fit in the arm pits was tight. I'd like to think it's my guns, but that's too optimistic. Seems they are just cut so that material pinches in, especially when armes are raised. Sort of irritating. Otehr than that, I love it for what it was designed to do. HH could add a couple of centimeters and make this perfect.

I used to work for Helly Hansen and I love this stuff! These shirts usually run very slim. They are advertised as being a "2nd Skin". So if that bothers you go a size up, and it will still be a little snug. You need them to be a little slimmer fitting because that is what makes them retain your body heat.

This shirt is absolutely perfect for snowboarding. I throw my Burton system jacket over it, and that's all I need in 15 degree F weather and high winds! I've taken this shirt out five times, and haven't gotten a chance to wash it, but there is no stench whatsoever. Hasn't stopped keeping me warm and dry either. I guess comfort is one of those things you can definitely buy.