100% Merino Wool
Here's what other sites are saying:
Cotton long underwear? Never. The 66 North Iceland Men's Basar Zip Neck Top keeps you warm and comfort with the power of our favorite fabric-100% merino wool. We're obsessed with this stuff. Merino insulates even when wet, works hard to regulate your temperature, and won't hold odors like synthetic materials. Flatlock stitching and an athletic fit make this midweight long underwear top easy to layer, and a -zip releases extra heat when you're working extra hard.
- Backcountry Outlet refers to the men's version