The moment I put on the Smartwool NTS Henley I was hooked. The instant this baselayer touched my skin, I knew this wasn't an ordinary baselayer. Beyond the feel, which is amazing by the way, the wool does so much more for you. It naturally pulls moisture away from the skin, which is vital during winter runs when sweat can rob heat from the body if it stays near your skin. Next, it's naturally antimicrobial, so you can wear it multiple days without having to wash it. It's also the most breathable material available today. I'll admit I wasn't sure about the Merino wool thing, but after wearing this Smartwool Henley I'm a believer.