Icebreaker base layers and long underwear are made of merino wool. You probably already knew that. You probably also already know what makes merino wool so awesome (you are so very smart), but I'm going to tell you again anyway. The awesomeness of Icebreaker baselayers all revolves around moisture, temperature and odor control.
First off, moisture control. Icebreaker base layers wick moisture like crazy. That might not seem like a huge issue when you're using baselayers to keep warm, but it totally is. Even when it's cold, your body still produces heat and moisture. Synthetic fabrics can leave you feeling clammy, which makes you colder, but not Icebreaker merino wool. Icebreaker long underwear draws moisture vapor to the outside of the garment before it condenses to sweat, so your skin stays dry and comfortable.
Temperature control is of course super important for base layer clothing; Icebreaker excels here, too. Just like the moisture, Icebreaker wicks away heat when your body produces too much of it, so you don't overheat. At the same time, when it's super cold, or you're engaging in some lower intensity activity, Icebreaker base layers use their little air pockets to trap heat, keeping you toasty warm.
Finally, Icebreaker baselayer doesn't stink, both literally and figuratively, but really, it doesn't stink. Icebreaker merino naturally resists odor, and can we worn for days (even weeks) without washing. Icebreaker merino also has an exceptional warmth-to-weight ratio, so it's as warm as a heavy wool sweater, but no bulkier than your favorite lightweight tee or a pair of tights.
Icebreaker long underwear just kind of naturally kicks ass. Besides the stuff I mentioned above, merino is naturally fire safe, meaning it's among the least flammable fibers. Merino is sunsafe with a UPF (Ultraviolet Protection Rating) of at least 50; that's higher than cotton and most synthetics. Icebreaker thermal baselayers are easy to care for, just toss them in the washer every three wears or so and hang them to dry. And you don't have to worry about static cling with merino, it's naturally static resistant, so there's no clingy static ride-up. Everybody hates that.
Check out Icebreaker base layer tops and bottoms, as they come in both short and long sleeve and in several different weights, so there's a great base layer for any activity. Plus there are Icebreaker midlayers like zip tops and sweaters, so you can create a layering system and really get the most out of your Icebreaker merino clothing. Also check out Icebreaker pants and leggings. Those come in full-length and capris.